University of Tennessee, Knoxville University of Tennessee, Knoxville TRACE: Tennessee Research and Creative TRACE: Tennessee Research and Creative Exchange Exchange Doctoral Dissertations Graduate School 12-2018 Biochemical and transcriptomic characterization of glycoside Biochemical and transcriptomic characterization of glycoside hydrolases in hydrolases in Thermobia domestica Thermobia domestica and and Ctenolepisma Ctenolepisma longicaudata longicaudata Ratnasri Mallipeddi University of Tennessee, [email protected]Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Recommended Citation Recommended Citation Mallipeddi, Ratnasri, "Biochemical and transcriptomic characterization of glycoside hydrolases in Thermobia domestica and Ctenolepisma longicaudata. " PhD diss., University of Tennessee, 2018. https://trace.tennessee.edu/utk_graddiss/5290 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected].
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University of Tennessee, Knoxville University of Tennessee, Knoxville
TRACE: Tennessee Research and Creative TRACE: Tennessee Research and Creative
Exchange Exchange
Doctoral Dissertations Graduate School
12-2018
Biochemical and transcriptomic characterization of glycoside Biochemical and transcriptomic characterization of glycoside
hydrolases in hydrolases in Thermobia domesticaThermobia domestica and and Ctenolepisma Ctenolepisma
Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss
Recommended Citation Recommended Citation Mallipeddi, Ratnasri, "Biochemical and transcriptomic characterization of glycoside hydrolases in Thermobia domestica and Ctenolepisma longicaudata. " PhD diss., University of Tennessee, 2018. https://trace.tennessee.edu/utk_graddiss/5290
This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected].
1953) were reported to feed on paper and other cellulose-rich substrates. Degraded
cellulose fibers and avicel were microscopically observed in the guts of C. longicaudata and
T. domestica, respectively (Lindsay, 1940; Sabbadin et al., 2018). Gut fluids of Zygentoma
were characterized as including endoglucanase, β-glucosidase, amylase, maltase, sucrase
and lactase activities (Lasker and Giese, 1956; Zinkler and Götze, 1987). Although five
5
fungal and four bacterial species were found in the gut of T. domestica, only the fungus
Mycotypha microspore displayed cellulolytic activity (Woodbury and Gries, 2013a).
However, axenic C. lineata and defaunated T. domestica supported endogenous cellulase
production, suggesting the existence of endogenous cellulases (Lasker and Giese, 1956;
Treves and Martin, 1994). In fact, T. domestica can digest cellulose in a symbiont-
independent manner, but needs the aid of microbes in accessing cellulosic substrates
(Woodbury and Gries, 2013b). More recently, Sabbadin et al (2018) investigated the
digestive proteome of T. domestica and identified carbohydrate degrading enzymes
including lytic polysaccharide monooxygenases (LPMOs), which weaken cellulose fibers
making them more accessible to cellulose degradation. Even though members of
Zygentoma were found to have diverse cellulolytic activities for efficient cellulose digestion
(Lasker and Giese, 1956; Zinkler and Götze, 1987), molecular evidence confirming
endogenous production of these cellulases is still lacking.
The goals of the present study were to provide a morphohistological
characterization of digestive system, biochemical characterization of highly active cellulase
enzymes in digestive fluids, to annotate and screen for PCWDEs genes present in T.
domestica and C. longicaudata genomes and to study their differential expression in foregut
and rest of the body samples when T. domestica and C. longicaudata were fed on four diets
with varying degree of cellulosic content.
6
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Lasker, R., Giese, A.C., 1956. Cellulose Digestion By The Silverfish Ctenolepisma Lineata. J. Exp. Biol. 33, 542–553.
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Lee, S.J., Kim, S.R., Yoon, H.J., Kim, I., Lee, K.S., Je, Y.H., Lee, S.M., Seo, S.J., Dae Sohn, H., Jin, B.R., 2004. cDNA cloning, expression, and enzymatic activity of a cellulase from the mulberry longicorn beetle, Apriona germari. Comp. Biochem. Physiol. B Biochem. Mol. Biol. 139, 107–116. https://doi.org/10.1016/j.cbpc.2004.06.015
Lindsay, E., 1940. The Biology of the Silverfish, Ctenolepisma longicaudata Esch. with particular Reference to its feeding Habits. Proc. R. Soc. Vic. 52.
Martin, M.M., 1991. The evolution of cellulose digestion in insects. Phil Trans R Soc Lond B 333, 281–288. https://doi.org/10.1098/rstb.1991.0078
Martin, M.M., Martin, J.S., 1978. Cellulose Digestion in the Midgut of the Fungus-Growing Termite Macrotermes natalensis: The Role of Acquired Digestive Enzymes. Science 199, 1453–1455. https://doi.org/10.1126/science.199.4336.1453
Modder, W.W.D., 1975. Feeding and growth of Acrotelsa collaris (Fabricius) (Thysanura, Lepismatidae) on different types of paper. J. Stored Prod. Res. 11, 71–74. https://doi.org/10.1016/0022-474X(75)90042-9
Oppert, C., Klingeman, W.E., Willis, J.D., Oppert, B., Jurat-Fuentes, J.L., 2010. Prospecting for cellulolytic activity in insect digestive fluids. Comp. Biochem. Physiol. B Biochem. Mol. Biol. 155, 145–154. https://doi.org/10.1016/j.cbpb.2009.10.014
Rouland, C., Civas, A., Renoux, J., Petek, F., 1988. Purification and properties of cellulases from the termite Macrotermes mülleri (termitidae, macrotermitinae) and its symbiotic fungus termitomyces sp. Comp. Biochem. Physiol. Part B Comp. Biochem. 91, 449–458. https://doi.org/10.1016/0305-0491(88)90004-1
Rouland, C., Lenoir, F., Lepage, M., 1991. The role of the symbiotic fungus in the digestive metabolism of several species of fungus-growing termites. Comp. Biochem. Physiol. A Physiol. 99, 657–663. https://doi.org/10.1016/0300-9629(91)90146-4
Sabbadin, F., Hemsworth, G.R., Ciano, L., Henrissat, B., Dupree, P., Tryfona, T., Marques, R.D.S., Sweeney, S.T., Besser, K., Elias, L., Pesante, G., Li, Y., Dowle, A.A., Bates, R., Gomez, L.D., Simister, R., Davies, G.J., Walton, P.H., Bruce, N.C., McQueen-Mason, S.J., 2018. An ancient family of lytic polysaccharide monooxygenases with roles in arthropod development and biomass digestion. Nat. Commun. 9, 756. https://doi.org/10.1038/s41467-018-03142-x
Sahrhage, D., 1953. Okologische Untersuchengen an Thermobia domestica (Packard) und Lepisma saccharina L. Z Wiss Zool 157, 77–168.
Terry, M.D., Whiting, M.F., 2005. Mantophasmatodea and phylogeny of the lower neopterous insects. Cladistics 21, 240–257. https://doi.org/10.1111/j.1096-0031.2005.00062.x
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Tomme, P., Warren, R.A.J., Gilkes, N.R., 1995. Cellulose Hydrolysis by Bacteria and Fungi, in: Poole, R.K. (Ed.), Advances in Microbial Physiology. Academic Press, pp. 1–81. https://doi.org/10.1016/S0065-2911(08)60143-5
Treves, D.S., Martin, M.M., 1994. Cellulose digestion in primitive hexapods: Effect of ingested antibiotics on gut microbial populations and gut cellulase levels in the firebrat,Thermobia domestica (Zygentoma, Lepismatidae). J. Chem. Ecol. 20, 2003–2020. https://doi.org/10.1007/BF02066239
Watanabe, H., Noda, H., Tokuda, G., Lo, N., 1998. A cellulase gene of termite origin. Nat. Lond. 394, 330–1. http://dx.doi.org/10.1038/28527
Watanabe, H., Tokuda, G., 2010. Cellulolytic Systems in Insects. Annu. Rev. Entomol. 55, 609–632. https://doi.org/10.1146/annurev-ento-112408-085319
Woodbury, N., Gries, G., 2013a. Firebrats, Thermobia domestica, aggregate in response to the microbes Enterobacter cloacae and Mycotypha microspora. Entomol. Exp. Appl. 147, 154–159. https://doi.org/10.1111/eea.12054
Woodbury, N., Gries, G., 2013b. How Firebrats (Thysanura: Lepismatidae) Detect and Nutritionally Benefit From Their Microbial Symbionts Enterobacter cloacae and Mycotypha microspora. Environ. Entomol. 42, 860–867. https://doi.org/10.1603/EN13104
Zinkler, D., Götze, M., 1987. Cellulose digestion by the firebrat Thermobia domestica. Comp. Biochem. Physiol. Part B Comp. Biochem. 88, 661–666. https://doi.org/10.1016/0305-0491(87)90360-9
9
Chapter 2
The digestive system in Zygentoma as a model for high cellulase activity
10
Ratnasri Pothula; O. P. Perera, William E. Klingeman; Heba M. Y. Abd-Elgaffar; Brian R.
Johnson and Juan Luis Jurat-Fuentes
My contributions included: (1) planning and performing experiments, (2) data collection
and analysis, (3) writing the manuscript and making figures. O. P. Perera helped with 2 and
3, Brian R. Johnson assisted with 3, William E. Klingeman provided insects and assisted
with 3, Heba M. Y. Abd-Elgaffar helped with histology and Juan Luis Jurat-Fuentes assisted
with 1, 2 and 3.
Abstract
The digestive system of phytophagous insects is expected to include novel
cellulolytic enzymes that may improve industrial cellulose degradation. While much
research has been performed on model insects such as termites and roaches, there is
dearth of information on cellulolytic systems in insects belonging to basal hexapod groups.
As part of a screening effort to identify insects with highly active cellulolytic systems, we
detected species of Zygentoma as displaying the highest relative cellulolytic activity levels
compared to all other tested insect orders including Blattodea. The goal of the present
study was to provide a morphohistological characterization of cellulose digestion and to
identify highly active cellulase enzymes in digestive fluids in two species of Zygentoma, the
firebrat (Thermobia domestica) and the gray silverfish (Ctenolepisma longicaudata).
Morphohistological characterization supported no relevant differences in the digestive
tube of T. domestica and C. longicaudata. Quantitative and qualitative cellulase assays
identified the foregut as the region with the highest cellulolytic activity in both the tested
insects, yet T. domestica was found to have higher endoglucanase, xylanase and pectinase
11
activities compared to C. longicaudata. In summary, we identify that the firebrat is a
member of zygentoma displaying highest relative cellulolytic activity compared to other
insect orders including model insects for cellulolytic research. Additionally, digestive fluids
of firebrat displayed higher cellulase, xylanase and pectinase activities, which are
necessary for efficient plant cell wall degradation. These findings advance our
understanding of cellulose digestion in a basal hexapod group and identify novel
cellulolytic enzymes with potential application in industrial cellulose digestion.
Introduction
The digestive system of phytophagous insects is considered a relevant prospecting
resource for identification of new cellulolytic enzymes to improve cellulose degradation to
glucose, a step accounting for >40% of production costs of ethanol biofuel from plant
biomass (Zhu et al., 2009; Bekmuradov et al., 2014). Cellulose is a linear polymer of D-
glucopyranosyl units linked by β-1,4 linkages that is degraded to glucose subunits by the
combined action of three types of enzymes, based on their mode of action and substrate
specificities. Endoglucanases (EC 3.2.1.4) cut at random internal points in cellulose chains,
while exoglucanases (EC 3.2.1.91) cleave at the non-reducing ends releasing cellobiose
units that are digested to glucose by β-glucosidases (EC 3.2.1.21) (Watanabe and Tokuda,
2010). Although research on cellulolytic systems in insects was initially confined to
symbiotic microorganisms (Cleveland, 1924), in the last decade insect endogenous plant
cell wall degrading enzymes (PCWDEs) have been described in Isoptera, Blattaria,
Coleoptera, Orthoptera, Pthiraptera, Hemiptera, Phasmatodea, Lepidoptera, Diptera and
Hymenoptera (Watanabe and Tokuda, 2010, Calderón-Cortés et al., 2012, Fischer et al.,
12
2013, and Chatterjee et al., 2015). Much of the research on insect cellulolytic enzymes has
concentrated on Isoptera, Blattodea, Coleoptera, Lepidoptera and Diptera, probably due to
the availability of sequenced genomes and other metagenomic resources (Davison and
Blaxter, 2005; Watanabe and Tokuda, 2010). In contrast, cellulolytic systems in other
insect orders that contain species specialized to feed on plant material are understudied
(Terry and Whiting, 2005). As part of a screening effort to identify insects with highly
active cellulolytic systems (Oppert et al., 2010), we detected species of Zygentoma as
displaying the highest relative cellulolytic activity levels compared to all other tested insect
orders.
Members of Zygentoma are known to feed and digest highly cellulosic materials
such as paper, cardboard, flour and insulation (Berger 1945 and Sahrhage 1953).
Description of the digestive system in Ctenolepisma campbelli and Lepisma saccharinum
supported similarities with Orthoptera, including slightly longer than body length,
differentiated into foregut, midgut and hindgut, and presence of a muscular proventriculus
with sclerotized teeth like structures (Barnhart, 1961). Production of endogenous
cellulases was previously reported in Ctenolepisma lineata and the firebrat, Thermobia
domestica (Lasker and Giese 1956; Zinkler and Götze 1987; Treves and Martin 1994).
Additionally, the crop was characterized as displaying the highest cellulolytic activity
compared to other digestive regions in T. domestica (Zinkler and Götze, 1987). More
recently, Sabbadin et al (2018) investigated the digestive proteome of T. domestica and
identified carbohydrate degrading enzymes including lytic polysaccharide
13
monooxygenases (LPMOs), which weaken cellulose fibers making them more accessible to
cellulose degradation.
The goal of the present study was to provide a morphohistological and biochemical
characterization of cellulose digestion in Zygentoma. Initial characterization supported no
relevant morphological differences in the digestive tube of the firebrat (T. domestica) and
the gray silverfish (Ctenolepisma longicaudata). Quantitative and qualitative cellulase
assays identified the foregut as the region with the highest cellulolytic activity and T.
domestica as displaying higher endoglucanase, xylanase and pectinase activities compared
to C. longicaudata. These findings advance our understanding of cellulose digestion in a
basal hexapod group and the identification of novel cellulolytic enzymes with potential
application in industrial cellulose digestion.
Materials and methods
Insects
Adult silverfish (Ctenolepisma longicaudata) and firebrat (Thermobia domestica)
were used for different objectives in this study. Nymphs and adults of C. longicaudata were
0.01% bromophenol blue) and the mixture was heated at 720C for 15 min to partially
denature proteins. Commercial cellulase from Aspergillus niger (Tokyo Chemical Industry
Co., Ltd., Portland, OR) was used as positive control. Samples were resolved by
electrophoresis at 100 V until the dye reached the bottom of the gel and the gels were
16
washed in 50 ml of 0.1 M Sodium succinate buffer (pH 5.8) containing 10 mM Dithiothreitol
(DTT) for five washes of 30 min with constant shaking. Gels were then incubated in 0.1 M
Sodium succinate buffer (pH 5.8) with no DTT for 30 min at 600C and then stained with
0.1% of Congo red (Acros Organics, Waltham, MA) for 10 min. Gels were destained by
incubating in 50 ml of 1 M NaCl until the cellulolytic activity bands were clearly visible as
clear bands on a red background. Glacial acetic acid (100 µl) was added to shift the
background gel color to dark-purple for more clear observation of activity bands. Gel
images were taken with a Versadoc 1000 Imager (Bio-Rad, Hercules, CA).
Quantification of cellulolytic, xylanase and pectinase activities
Quantitative activity against carboxymethylcellulose (CMC) in gut fluids of diverse
insects (shown in Fig. 2.1A) was determined as described in Oppert et al. (2010). Assays
with gut fluids from C. longicaudata were performed concomitantly but were not originally
included in Oppert et al (2010). In the present study, the protein content in dissected head
and foregut samples was quantified using the Protein Quantification kit in a Qubit
fluorometer (Invitrogen, Carlsbad, CA). Cellulose degrading activity in head and foregut
tissues of C. longicaudata and T. domestica was quantified using a cellulase assay kit
(Megazyme, Ireland) to quantify endoglucanase activity against 4-nitrophenyl-β-D-
cellopentaoside (BPNPG5) as substrate, 4-nitrophenyl β-D-cellobioside (pNPC) (Sigma-
Aldrich, St. Louis, MO) as substrate for β-glucosidase, 4-nitrophenyl β-D-xylopyranoside
(pNPX) (Sigma-Aldrich, St. Louis, MO) as substrate to quantify xylanase activity, and pectin
from citrus peel (Sigma-Aldrich, St. Louis, MO) to measure pectinase activity.
17
Briefly, β-glucosidase and xylanase activities were measured in samples (20 µl
containing 10 µg of protein) mixed with 130 µl of 10 mM substrate in 50 mM sodium
acetate buffer (pH 5.0), and incubated at 500C for 30 min. To a 50 µl aliquot of reaction
mixture, 50 µl of 2 M Na2CO3 was added to stop the reaction and absorbance was measured
at 405 nm in a Synergy HT microplate reader (BioTek, Winooski, VT) using the Gen5
software (v. 2.0, BioTek, Winooski, VT). A 4-nitrophenol standard curve (0-1 mM) was used
to quantify specific activity and background activity was corrected by subtracting final
values from initial values. Specific activity was expressed in U/mg of protein, with 1 U
defined as the amount of enzyme resulting in production of 1 µmol of 4-nitrophenol per
min at pH 5.0 and 500C.
Endoglucanase activity was measured in samples (5 µg of protein in 25 µl) mixed
with 50 µl of substrate and incubated at 400C for 10 min. Reactions were terminated by
adding alkaline solution (125 µl of Tris buffer solution pH 9.0) and absorbance was
measured at 405 nm as above. Activity was calculated according to the Mega-Calc method
from the manufacturer (https://secure.megazyme.com/Cellulose-Assay-Kit-CELLG5-
Method).
Pectinase activity was determined in samples (10 µg of protein in 20 µl) mixed with
15 µl of 1% pectin and 115 µl of 50 mM sodium acetate buffer (pH 5.0). The mixture was
incubated at 500C for 1 h, and then 50 µl of 3,5-Dinitrosalicylic acid (DNSA) reagent was
added and absorbance measured at 540 nm as above. The specific activity was calculated
using a glucose standard curve (0-20 mM) and background activity was corrected by
subtracting final values from initial values. Specific activity was expressed in U/mg of
18
protein, with 1 U defined as the amount of enzyme resulting in production of 1 µmol of
glucose per min at pH 5.0 and 500C.
All activity assays were carried out using at least three biological and three technical
replicates. The statistical design for each activity assay was a completely randomized
design with a 2x2x2 factorial. Statistical analyses were performed through SAS (SAS
Institute, Inc., Cary, NC) using a mixed model analysis of variance. Prior to analysis, data
that failed to pass the Shapiro-Wilk normality test were log transformed. Least square
means were separated using Tukey’s option and significant differences were considered at
P < 0.05.
Results
High cellulase activity and gut morphology and histology in Zygentoma
As a part of a quantitative prospecting effort to identify insects with high cellulolytic
activity (Oppert et al., 2010), we detected species in Zygentoma as having the highest
relative cellulolytic (endoglucanase, CMCase) activity among all taxonomic orders tested
(Fig. 2.1A).
The digestive systems of two species of Zygentoma, T. domestica and C. longicaudata
had similar morphology and histology, although the digestive tube in C. longicaudata was
longer and larger than in T. domestica (Fig. 2.1B). Consequently, we focused on C.
longicaudata for further characterization of the digestive tube due to its relatively bigger
size. This digestive tube was longer than the insect body length and could be divided into
foregut, midgut and hindgut regions. The foregut was the largest part of the digestive
system and included an enlarged crop extending throughout the thoracic region and
19
making up half of the digestive tube (Fig. 2.1C). It was observed in most dissections that
among the three gut compartments, the food bolus was always found in the crop.
Histological observations of the crop wall in C. longicaudata identified a monolayer
of epidermal cells supported by circular muscle cells (Fig. 2.2 A). The crop opened
posteriorly into the proventriculus, which was highly muscular and had six sclerotized
teeth-like structures (Fig. 2.2 B). The midgut was the second longest part of digestive
system and appeared as a simple tube-like structure with gastric caecae at the anterior
region. The midgut wall was characterized by the presence of a single layer of columnar
cells with apical brush border membrane, and nidi of stem cells appeared interspersed in
the epithelium (Fig. 2.2 C). The connection between midgut and hindgut was traced by the
presence of Malpighian tubules, which were numerous in number and longer than the
insect body length (Fig. 2.1 B). The hindgut was also short and simple tube-like structure
with a monolayer of epidermal cells and ended in rectal pads (Fig. 2.2 D).
Qualitative and quantitative detection of cellulolytic activity in the digestive system
of T. domestica and C. longicaudata
Zymograms of T. domestica gut fluids had more and brighter bands of activity
against CMC compared to C. longicaudata (Fig. 2.3). When comparing among gut regions,
higher cellulolytic activity was found in samples from the head and foregut compared to
midgut and hindgut tissues (Fig. 2.3). Consequently, head and foregut tissues were selected
for quantitative enzymatic assays for plant cell wall degrading enzyme (PCWDE) activities.
Activities tested quantitatively included endoglucanase, β-glucosidase, xylanase and
pectinase in digestive fluids obtained from head and foregut samples of both T. domestica
20
and C. longicaudata (Fig. 2.4). As observed in the qualitative zymograms, digestive fluids
from both head and foregut tissues of T. domestica had significantly higher endoglucanase
activity compared to C. longicaudata (P < 0.05). Within T. domestica, the digestive fluids
from the foregut had significantly higher endoglucanase activity than fluids from head
tissue (P < 0.05), while significant differences were not observed between samples from
foregut and head tissues of C. longicaudata (Fig 2.4 A). Both T. domestica and C.
longicaudata had no β-glucosidase activity in head fluids, however similar levels of β-
glucosidase activity were found in the digestive fluids from foregut tissues of both species
(Fig 2.4 B). Xylanase activity was significantly higher (about six-fold, P < 0.05) in the
foregut fluids of T. domestica compared to C. longicaudata, and very small levels of xylanase
activity were detected in head fluids from both insects (Fig. 2.4 C). Pectinase activity was
absent from C. longicaudata and present in both head and foregut tissues of T. domestica
(Fig. 2.4 D). Feeding both insects on a protein-rich (BSA) or a cellulose-rich (paper) diet did
not result in significant differences in any of the tested enzyme activities (P > 0.05) (Fig.
2.4).
Discussion
Members of Zygentoma displayed significantly higher (>4-fold) cellulase activity
compared to species in taxonomic orders traditionally considered as insect models for
cellulase research, such as Coleoptera, Blattodea and Isoptera. Zygentoma is a basal
hexapod group known to feed on highly lignocellulosic substrates (Berger, 1945) and to
produce endogenous cellulases (Lasker and Giese, 1956; Zinkler and Götze, 1987; Treves
and Martin, 1994). Recently, T. domestica has been identified to endogenously produce lytic
21
polysaccharide monooxygenases (LPMOs) in addition to carbohydrate degrading enzymes
(Sabbadin et al., 2018), which may explain the relatively highest cellulolytic activity in this
group.
Although both T. domestica and C. longicaudata belong to Zygentoma and have
similar digestive system morphology, we detected significant differences in cellulose
activity between these species. Within a species, we also detected significant differences
among fluids from different digestive regions in their ability to degrade different plant cell
wall substrates. Nevertheless, in both the insect species the highest levels of enzymatic
activity against the tested substrates were detected for digestive fluids from foregut
compared to any other tissue in the digestive system. This observation is also supported by
previous reports documenting higher endoglucanase and β-glucosidase activities in the
foregut compared to other gut tissues in T. domestica (Zinkler and Gotze, 1987) and
Acrotelsa collaris (Modder, 1964). In addition, cellulose fibers were reported to be digested
in the crop of C. longicaudata (Lindsay, 1940). Localization of the main cellulolytic activity
(endoglucanase, CMCase) to the foregut has also been reported in other arthropod groups,
such as millipedes (Chicobulus sp.), desert locust (Schistocerca gregaria) and a longhorn
beetle (Hylotrupes bajules) (Cazemier et al., 1997). In contrast, Lasker and Giese (1956)
reported no cellulolytic activity in the fluids from the crop of Ctenolepisma lineata.
Interestingly, in our histological sections the gut secretory columnar cells were only found
in the midgut epithelium and were absent from the foregut. Recently, expression of LPMOs
was localized to salivary glands, crop and midgut tissues of T. domestica, with relatively
higher expression in the midgut tissue (Sabbadin et al., 2018). All these observations may
22
suggest that both LPMOs and cellulases may be produced in the midgut and foregut (crop),
although it is also possible that in some insects the enzymes may be secreted from midgut
cells but flow towards the foregut (Terra, 1990; Terra and Ferreira, 1994). Taken together,
the current evidence supports that the foregut is the most important tissue for plant cell
wall digestion in Zygentoma.
Diverse PCWDEs, including cellulases such as endoglucanases and β-glucosidases;
and hemicellulases like xylanases, were found in the digestive fluids of both T. domestica
and C. longicaudata. In addition, T. domestica displayed pectinase activity, which indicates
that T. domestica has all the necessary plant cell wall degrading enzymes to digest complex
cellulolytic substrates. Comparatively, T. domestica had significantly higher levels of
endoglucanase, xylanase and pectinase activities, which suggests a more efficient and
complex cellulolytic system compared to C. longicaudata.
Feeding T. domestica and C. longicaudata a cellulose-rich diet did not result in
increased production of cellulases, which suggests that cellulase production in these
insects is not driven by diet. Similar results were reported from a gut proteome analysis of
T. domestica fed on different cellulosic substrates, which did not alter production of
carbohydrate digesting enzymes but increased abundance of LPMOs when fed on
crystalline cellulose (Sabbadin et al., 2018). Consequently, it is plausible that in Zygentoma
the production of cellulases remains constant while the production of LPMOs could be
driven by the content of cellulose in the diet.
Identification of proteins in chromatographic fractions with CMCase activity in gut
fluids of T. domestica (Pothula et al, submitted) revealed the presence of endoglucanases
23
with similarity to enzymes from termites, beetles, and the herbivorous crustacean Daphnia
pulex. Firebrat was reported to associate with five fungal species (Mycotypha microspore,
Aspergillus ochraceus, Aspergillus niger and two species of Penicillium) and four bacterial
species (Enterobacter cloacae, Bacillus sps., Micrococcus sps., and Klebsiella sps.) (Woodbury
and Gries, 2013a). However, firebrats exhibit aggregation behavior only in the presence of
Enterobacter cloacae and Mycotypha microspore due to the presence of D-glucose
(Woodbury and Gries, 2013a). Of these two microbes, only the fungus Mycotypha
microspore was able to degrade cellulose into glucose and the bacterium Enterobacter
cloacae had D-glucose as a constituent of thick polysaccharide surface coating (Woodbury
and Gries, 2013b). However, feeding firebrats with antibiotics resulted in significant
reduction of gut microbial load but did not alter the cellulolytic activity of gut fluids (Treves
and Martin, 1994). These results suggest that firebrats can digest cellulose in a symbiont-
independent manner, but may need the aid of microbes in accessing cellulosic substrates.
Accordingly, most of the identified proteins with CMCase activity in firebrat gut fluids were
matched to insect genes (Pothula et al, submitted) indicating the endogenous origin of
cellulases. Exceptions to this observation included two glucan endo-1,6-beta-glucosidases
matching to Haloplasma contractile and Paenibacillus sp. JDR-2, which probably aid in
cellulose digestion in firebrats but further research is needed to confirm their role.
Overall, our work suggests that members of Zygentoma express a repertoire of
PCWDEs, including cellulases, xylanases and pectinases. Digestive fluids of T. domestica
appeared significantly more active than in C. longicaudata, in both insects the highest levels
of digestion were detected in the foregut. Considering the results in this work and the
24
dearth of information on Zygentoma, we propose the need for further research to learn
more on the evolution of PCWDE in these insects and test their capacity in prospecting for
new enzymes for use in production of industrial cellulose digestion.
25
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Appendix 2
32
Figure 2.1. Relative CMCase activity in Zygentoma compared to other insect orders and structural comparison of the digestive tract in firebrat (Thermobia domestica) and silverfish (Ctenolepisma longicaudata). A) Activity (U/mg) of gut digestive fluids against CMC substrate in the most active samples from species of Zygentoma (C. longicaudata), and representative species from Orthoptera (Conocephalus strictus), Lepidoptera (Halysidota tessellaris), Blattodea (formerly Isoptera): Rhinotermitidae (Reticulitermes flavipes), Hymenoptera (Neodiprion lecontei), Diptera (Monarthropalpus flavus), Dermaptera (Forficula auricularia), Coleoptera (Scolytinae spp.) and Blattodea (formerly Blattaria): Cryptocercidae (Cryptocercus spp.). Shown are the average activity and corresponding standard error from at least three biological replicates performed in triplicate for each species. All activity assay experiments were concurrent, but all activities except for the Zygentoma sample were taken from Oppert et al. (2010). B) Dissected digestive tracts of firebrat (top) and silverfish (bottom). Note the relatively larger size of the tract in silverfish compared to firebrat. C) Morphological parts of the digestive tract of firebrat. FG, foregut; MG, midgut; HG, hindgut; GC, gastric caecae; MT, Malpighian tubules.
33
Figure 2.2. Histology of the digestive system regions in Ctenolepisma longicaudata. A) Longitudinal section of the crop showing the monolayer of epidermal cells and the underlying circular muscle cells. B) Longitudinal section of proventriculus. C) Longitudinal section of midgut showing peritrophic membrane, columnar cells lined with brush border membrane and intermitted by a group of nidi cells at the bottom. D) Longitudinal section of hindgut wall showing the monolayer of epidermal cells. All sections were stained with hematoxylin and eosin stain. GC, gut cavity; CM, circular muscle cells; PTM, peritrophic matrix; CC, columnar cells; BBM, brush border membrane.
34
Figure 2.3. Detection of cellulolytic activity in digestive fluids of Thermobia domestica and Ctenolepisma longicaudata. Zymograms with 0.2% carboxymethyl cellulose were used to detect the cellulolytic (CMCase) activity in head, foregut, midgut and hindgut tissues of T. domestica (left) and C. longicaudata (right). Numbers indicate pre-stained protein molecular marker; +ve, commercial cellulase used as positive control; H, head; FG, foregut; MG, midgut; HG, hindgut.
35
Figure 2.4. Quantification of plant cell wall degrading enzyme activities in the fluids derived from head and foregut tissues of Ctenolepisma longicaudata and Thermobia domestica. Fluids from head and foregut (FG) tissues of C. longicaudata and T. domestica fed on protein (BSA) or paper diet (see Materials and Methods) were used in assays to detect A) endoglucanase activity against 4-nitrophenyl-β-D-cellopentaoside (BPNPG5), B) β-glucosidase activity against 4-nitrophenyl β-D-cellobioside (pNPC), C) xylanase activity against 4-nitrophenyl β-D-xylpyranoside (pNPX), and D) pectinase activity against pectin from citrus peel. Shown are the means and corresponding standard errors calculated from three biological and three technical replicates. Different letters above the bars indicate significant differences in the mean activity (P < 0.05). Units of specific enzyme activity are per mg of protein in all the graphs except in graph A) where it is expressed per g of protein. One unit of enzyme activity was defined as the amount of enzyme required to release 1 µmol of 4-nitrophenol from the respective substrate in all the graphs except in D), where it is 1 µmol of glucose.
36
Chapter 3
Annotation of plant cell wall degrading enzymes (PCWDEs) among coding sequences
from genomes of Thermobia domestica and Ctenolepisma longicaudata
37
Pothula, R.; Johnson, B.R.; Klingeman, W.E. and J.L. Jurat-Fuentes. (2018).
My contributions included: (1) planning and performing experiments, (2) data collection
and analysis, (3) writing the manuscript and making figures. Brian R. Johnson assisted with
2, William E. Klingeman provided insects and Juan Luis Jurat-Fuentes assisted with (1 and
2).
Abstract
In the last decade, insects have emerged as a prospecting resource for new plant cell
wall degrading enzymes (PCWDEs) given their endogenous production of cellulases,
hemicellulases and pectinases. Although insects belonging to 16 taxonomic orders have
been reported to have endogenous production of one or more of PCWDEs, molecular
evidence has confirmed the presence of PCWDEs in insects from only eight taxonomic
orders. We have identified members of Zygentoma as having the highest relative
cellulolytic activity against carboxymethylcellulose compared to other insect groups,
including termites and cockroaches. Consequently, in the present work our goal was to find
PCWDEs genes present in the Thermobia domestica and Ctenolepisma longicaudata
genomes. Annotation of predicted coding sequences from genomes of T. domestica and C.
longicaudata reported numerous genes encoding for endoglucanases, glucosidases, β-1,3-
glucanases, maltases, amylases, mannosidases, glucuronidases and lytic polysaccharide
monoxygenases (LPMOs), which may help explain the relatively high cellulolytic activity
displayed by these compared to other insects. Additionally, except LPMOs, the majority of
the coding sequences encoding for different glycoside hydrolases were most similar to
38
Blattodea, which indicates the conservation of PCWDE genes through evolution in insects.
Our study contributes to enhance the availability of annotated genetic information on
insect PCWDEs in general, and especially in a primitive insect group.
Introduction
Plant cell walls are composed of cellulose, hemicellulose, pectin and lignin. Cellulose
is considered the most available renewable energy source on earth (Lynd et al., 1991).
Many organisms, including insects, are able to feed and digest plant material to obtain
energy. In the last decade, insects have emerged as a prospecting resource for new plant
cell wall degrading enzymes (PCWDs) given their endogenous production of cellulases,
hemicellulases and pectinases (Calderón-Cortés et al., 2012; Watanabe and Tokuda, 2010).
Cellulases are a group of glycosyl hydrolase enzymes that aid in complete digestion
of cellulose to glucose, which in biorefineries can be fermented by yeast to generate
bioethanol. This group of enzymes includes endoglucanases, which cleave the cellulose
chain internally at random locations, exoglucanases that cleave the cellulose chain from the
ends releasing two molecules of glucose (cellobiose) and β-glucosidases, which degrade
cellobiose to glucose subunits (Watanabe and Tokuda, 2010). Hemicellulases and
pectinases are involved in the breakdown of hemicellulose and pectin polysaccharides,
respectively, which are interlocked with cellulose in plant material (Gilbert, 2010).
Insects belonging to 16 taxonomic orders have been reported to have endogenous
production of one or more of PCWDEs (Calderón-Cortés et al., 2012). However, molecular
evidence has confirmed the presence and characterized PCWDEs from species in only eight
taxonomic orders. These characterized enzymes include endoglucanases belonging to
39
glycoside hydrolase (GH) families 9 and 45, β-glucosidases of GH 5, hemicellulases such as
xyloglucanases of GH 5 and GH 11, β-1,3-glucanases of GH 16, and pectinases of GHF 28
(Calderón-Cortés et al., 2012). Therefore, there is still a dearth of molecular data for the
identification of endogenous cellulases in insects, especially from basal hexapod groups.
We have recently identified members of Zygentoma as having the highest relative
cellulolytic activity against carboxymethylcellulose compared to termites and cockroaches
(Chapter 2).
Zygentoma is a basal hexapod group, with members feeding on highly cellulosic
materials such as starch, paper and cardboard (Berger, 1945; Sahrhage, 1953). A
defaunation study on Ctenolepisma lineata and Thermobia domestica supported
endogenous production of cellulases in these species (Lasker and Giese, 1956; Treves and
Martin, 1994). Biochemical evidence indicates that digestive fluids, especially from the
foregut of T. domestica, contain endoglucanase, β-glucosidase, xylanase, pectinase, amylase,
maltase, sucrase and lactase activities (Zinkler and Götze, 1987; Chapter 2). In addition to
cellulases, investigation of the digestive proteome of T. domestica revealed the production
of lytic polysaccharide monoxygenases (LPMOs), which are predicted to soften the
cellulose fibers and make them more tractable to cellulases (Sabbadin et al., 2018). Even
though the firebrat (T. domestica) and the silverfish (Ctenolepisma longicaudata) have
similar gut morphohistology, T. domestica displayed higher cellulolytic activity than C.
longicaudata (Chapter 2). Consequently, in the present work our goal was to find
endogenous PCWDE genes in the genome and confirm their expression from
transcriptomes of T. domestica and C. longicaudata. Our analyses revealed that both T.
40
domestica and C. longicaudata contain and express numerous genes encoding for
(24), galactosidases (22), amylases (20), β-1,3-glucanases (15) and endo-1,4-beta-
xylanases (3).
Among oxidoreductases found in C. longicaudata 67 genes encoded for LPMOs (Fig.
3.10). Similar to T. domestica, the majority of LPMOs (55) in C. longicaudata closely
matched to T. domestica genes, with the remaining (12) coding sequences being most
similar to Hemiptera, Hymenoptera and other arthropods (Table 3.21). Except LPMOs, all
other coding sequences encoding for diverse glycoside hydrolases were most closely
matched to enzymes from other insects and arthropods members outside of Zygentoma.
The majority of endoglucanases, mannosidases, glucosidases, amylases, galactosidases,
myrosinases and glucuronidases were most closely matched to enzymes from termites and
cockroaches (Blattodea) (Table 3.11, 3.12, 3.14, 3.15, 3.17, 3.18 and 3.20). On the other
hand, the majority of β-1,3-glucanases and maltases were most similar to Blattodea and
non-insect arthropods (Table 3.13 and 3.16). Only three xylanases were found in C.
londicauadata, two of which matched to non-isect arthropods and one matched to a
hemipteran (Table 3.19).
Discussion
In our previous work (Chapter 2), we found that members of Zygentoma, especially
T. domestica, display highest relative cellulolytic activity compared to other insects,
including termites. In the present work, we present the annotation and identification of
PCWDEs from the genome of T. domestica and C. longicaudata as representative members
of Zygentoma. Annotation of all coding sequences for both T. domestica and C. longicaudata
revealed that about 1/3 of coding sequences in both species did not yield any blast hits,
46
which indicates the dearth of genetic information on primitive insect groups. Additionally,
most of the sequences encoding for PCWDEs had highest identity to genes in Blattodea
(termites and cockroaches), which suggests the conservation of genes encoding PCWDEs
through evolution.
Both T. domestica and C. longicaudata had numerous coding sequences encoding for
diverse glycoside hydrolases. However, T. domestica had 85 sequences encoding for
endoglucanases (Table 3.1) while C. longicaudata had 69 (Table 3.11), which may explain
the higher endoglucanase activity reported in T. domestica compared to C. longicaudata
(Chapter 2). On the other hand, genomes of both species yielded nearly equal number of β-
glucosidase genes (Table 3.2 and 3.12), which was reflected in similar enzyme activity
levels (Chapter 2).
In contrast to cellulases, xylanases are rarely described as endogenously produced
in insects (Calderón-Cortés et al., 2012). In agreement with this observation, only C.
longicaudata had three sequences matching to xylanases, while T. domestica had no coding
sequences encoding for xylanases. However, it is possible that hemicellulose could be
digested in these insects by other enzymes, such as mannanases, α-glucuronidases,
endoglucanases and β-1,3-glucanases, which were present in both species (Calderón-
Cortés et al., 2012). Similarly, pectinases, which are not commonly found in insects, were
absent from T. domestica and C. longicaudata. One possibility to explain the lack of
pectinases may be that they may be produced by microorganisms present in the gut fluids.
In addition to cellulases, several enzymes involved in digestion of starch and other
polysaccharides, such as maltases, amylases, and mannosidases, were found in both
47
species. The highest number of sequences among these enzyme groups was found for
myrosinases, which play an important role in plant defense against herbivores (Husebye et
al., 2005). Myrosinases have also been reported from aphids and the crystal structure of a
myrosinase from Brevicoryne brassicae revealed its highest similarity with β-glucosidase
(Bones and Rossiter, 1996; Husebye et al., 2005). In our analysis, although the sequence
descriptions matched to myrosinases, in most instances the corresponding blast-hit
description identified the sequence as a β-glucosidase (Table 3.9 and 3.20).
Both T. domestica and C. longicaudata were found to encode LPMOs, with 59 and 67
sequences identified, respectively. In comparison, a previous study on the digestive
proteome and transcriptome of T. domestica was able to identify and annotate 21 LPMO
genes (Sabbadin et al., 2018). Moreover, in our study we found 9 and 12 coding sequences
of T. domestica and C. longicaudata, respectively, matching to LPMOs in other insect orders
and to other arthropod groups, which probably indicates the depth of our genome
coverage.
Overall, the genomes of T. domestica and C. longicaudata yielded a diverse array of
PCWDEs, which indicate their ability to breakdown and digest cellulose completely. The
presence of a high number of endoglucanases and β-glucosidases in both insect species
could explain their relatively higher cellulolytic activity compared to other insect groups
(Table 3.22). Although most of the PCWDE encoding sequences had highest identity to
genes from Blattodea, numerous sequences from all enzyme classes matched to other
arthropod groups including primitive collembola as well as highly and recently evolved
insects such as hymenopterans. The extent of PCWDE homology within Inecta and other
48
arthropod groups may suggest the evolution of cellulases in insects from a common
ancestor rather than through horizontal transfer from microbes. This work contributes to
increase the availability of insect glycosyl hydrolase annotated sequences in general, and
especially for a primitive insect group.
49
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55
Appendix 3
56
Table 3.1. Endoglucanases in Thermobia domestica: Coding sequences in T. domestica genome encoding for endoglucanases and their blast description.
gi|1330895262|gb|PNF24409.1|hypothetical protein B7P43_G09674, partial [Cryptotermes secundus] Blattodea
PNF24409
6.72E-12
94.87179
72.0182 39 37
60
Table 3.1. Continued.
Sequence name
Sequence desc.
Sequence length Hit desc. Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00041503-RA
AChain A, The Structure Of Endoglucanase From Termite, Nasutitermes Takasagoensis, At Ph 2.5.
1160
gi|28373491|pdb|1KS8|AChain A, The Structure Of Endoglucanase From Termite, Nasutitermes Takasagoensis, At Ph 2.5.gi|28373492|pdb|1KSC|AChain A, The Structure Of Endoglucanase From Termite, Nasutitermes Takasagoensis, At Ph 5.6.gi|28373493|pdb|1KSD|AChain A, The Structure Of Endoglucanase From Termite, Nasutitermes Takasagoensis, At Ph 6.5. Blattodea
1KS8_A, 1KSC_A, 1KSD_A
5.6E-143
73.5376
418.698 359 264
61
Table 3.1. Continued.
Sequence name
Sequence desc.
Sequence length Hit desc. Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00068682-RA
endoglucanase E-4-like
1007
gi|1339056265|ref|XP_023716596.1|uncharacterized protein LOC111869358 [Cryptotermes secundus]gi|1339056267|ref|XP_023716597.1|uncharacterized protein LOC111869358 [Cryptotermes secundus]gi|1330895261|gb|PNF24408.1|hypothetical protein B7P43_G09674 [Cryptotermes secundus] Blattodea
XP_023716596, XP_023716597, PNF24408
1.9E-121
90.55794
362.844 233 211
Th_d_00000353-RA
Endoglucanase A
1836
gi|1339087696|ref|XP_023704929.1|uncharacterized protein LOC111863126 [Cryptotermes secundus]gi|1330920323|gb|PNF36365.1|Endoglucanase A [Cryptotermes secundus] Blattodea
gi|1339087696|ref|XP_023704929.1|uncharacterized protein LOC111863126 [Cryptotermes secundus]gi|1330920323|gb|PNF36365.1|Endoglucanase A [Cryptotermes secundus] Blattodea
XP_023704929, PNF36365
1.5E-126
63.70023
379.407 427 272
Th_d_00040844-RA
Endoglucanase A
1860
gi|1339087696|ref|XP_023704929.1|uncharacterized protein LOC111863126 [Cryptotermes secundus]gi|1330920323|gb|PNF36365.1|Endoglucanase A [Cryptotermes secundus] Blattodea
uncharacterized family 31 glucosidase KIAA1161-like 468
gi|1101351520|ref|XP_018901738.1|PREDICTED: uncharacterized family 31 glucosidase KIAA1161-like [Bemisia tabaci]
Hemiptera
XP_018901738
5.7E-24
86.15385
103.219 65 56
Th_d_00098342-RA
uncharacterized family 31 glucosidase KIAA1161-like 396
gi|646703149|gb|KDR11965.1|hypothetical protein L798_13618, partial [Zootermopsis nevadensis]
Blattodea
KDR11965
1.63E-49
81.41593
170.629 113 92
81
Table 3.2. Continued.
Sequence name
Sequence desc.
Sequence length Hit desc. Order
Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00018632-RA
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product
1317
gi|303324839|pdb|3AHZ|AChain A, Crystal Structure Of Beta-Glucosidase From Termite Neotermes Koshunensis In Complex With Trisgi|393715252|pdb|3VIF|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Gluconolactonegi|393715253|pdb|3VIG|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With 1-deoxynojirimycingi|393715254|pdb|3VIH|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Glycerolgi|393715255|pdb|3VII|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Bis-tris Blattodea
3AHZ_A, 3VIF_A, 3VIG_A, 3VIH_A, 3VII_A
4.1E-180
75.23148
517.309
432 325
82
Table 3.2. Continued.
Sequence name
Sequence desc.
Sequence length Hit desc.
Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00057277-RA
uncharacterized family 31 glucosidase KIAA1161-like 426
gi|646703149|gb|KDR11965.1|hypothetical protein L798_13618, partial [Zootermopsis nevadensis]
uncharacterized family 31 glucosidase KIAA1161 1347
gi|1228003695|ref|XP_021933733.1|uncharacterized family 31 glucosidase KIAA1161-like isoform X1 [Zootermopsis nevadensis]gi|646703150|gb|KDR11966.1|putative family 31 glucosidase [Zootermopsis nevadensis]
Blattodea
XP_021933733, KDR11966
1.7E-121
54.18251
374.785 526 285
Th_d_00000860-RA
neutral alpha-glucosidase AB 414
gi|1339041694|ref|XP_023710162.1|neutral alpha-glucosidase AB [Cryptotermes secundus]gi|1330933432|gb|PNF42738.1|Neutral alpha-glucosidase AB [Cryptotermes secundus]
Blattodea
XP_023710162, PNF42738
3.75E-55
82.44275
191.045 131 108
Th_d_00000862-RA
Neutral alpha-glucosidase AB 435
gi|1227991790|ref|XP_021927674.1|neutral alpha-glucosidase AB isoform X2 [Zootermopsis nevadensis]
Blattodea
XP_021927674
1.85E-46
85.59322
166.777 118 101
Th_d_00000861-RA
Neutral alpha-glucosidase AB 315
gi|1227991792|ref|XP_021927675.1|neutral alpha-glucosidase AB isoform X3 [Zootermopsis nevadensis]gi|646709565|gb|KDR15365.1|Neutral alpha-glucosidase AB [Zootermopsis nevadensis]
Blattodea
XP_021927675, KDR15365
7.97E-23
94.11765
97.4413 51 48
84
Table 3.2. Continued.
Sequence name
Sequence desc.
Sequence length Hit desc.
Order
Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00000863-RA
Neutral alpha-glucosidase AB 519
gi|930677078|gb|KPJ17206.1|Neutral alpha-glucosidase AB [Papilio machaon]
Lepidoptera
KPJ17206
1.18E-53
80.53097
173.711 113 91
Th_d_00000865-RA
neutral alpha-glucosidase AB 1599
gi|1339041694|ref|XP_023710162.1|neutral alpha-glucosidase AB [Cryptotermes secundus]gi|1330933432|gb|PNF42738.1|Neutral alpha-glucosidase AB [Cryptotermes secundus]
Blattodea
XP_023710162, PNF42738
1.4E-103
70.22059
337.421 272 191
Th_d_00000864-RA
Neutral alpha-glucosidase AB 633
gi|242019253|ref|XP_002430076.1|Neutral alpha-glucosidase AB precursor, putative [Pediculus humanus corporis]gi|212515157|gb|EEB17338.1|Neutral alpha-glucosidase AB precursor, putative [Pediculus humanus corporis]
Phthiraptera
XP_002430076, EEB17338
2.81E-42
74.25743
157.147 101 75
Th_d_00000866-RA
Neutral alpha-glucosidase AB 780
gi|1108484091|emb|CRK87777.1|CLUMA_CG001536, isoform A [Clunio marinus]
Uncharacterized family 31 glucosidase KIAA1161 2302
gi|636630780|gb|AIA09350.1|alpha-glucosidase family 31, partial [Periplaneta americana] Blattodea AIA09350
6.9E-176
69.02287
523.472 481 332
92
Table 3.2. Continued.
Sequence name
Sequence desc.
Sequence length Hit desc. Order
Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00159760-RA
lysosomal alpha-glucosidase-like 903
gi|1330905640|gb|PNF29605.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905643|gb|PNF29608.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905644|gb|PNF29609.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus] Blattodea
PNF29605, PNF29608, PNF29609
9.96E-54
59.93266
187.193 297 178
Th_d_00127607-RA
lysosomal alpha-glucosidase-like 903
gi|1330905640|gb|PNF29605.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905643|gb|PNF29608.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905644|gb|PNF29609.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus] Blattodea
gi|195377741|ref|XP_002047646.1|uncharacterized protein Dvir_GJ11812 [Drosophila virilis]gi|194154804|gb|EDW69988.1|uncharacterized protein Dvir_GJ11812 [Drosophila virilis] Diptera
XP_002047646, EDW69988
8.58E-16
97.05882
76.6406 34 33
Th_d_00080493-RA
lysosomal alpha-mannosidase-like 1059
gi|642940243|ref|XP_008199468.1|PREDICTED: RNA-directed DNA polymerase from mobile element jockey-like, partial [Tribolium castaneum]
Coleoptera
XP_008199468
6.87E-22
55.42169
100.523 166 92
98
Table 3.4. Continued.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00121568-RA
ER degradation-enhancing alpha-mannosidase-like protein 3 402
gi|242016705|ref|XP_002428888.1|predicted protein [Pediculus humanus corporis]gi|212513656|gb|EEB16150.1|predicted protein [Pediculus humanus corporis]
Phthiraptera
XP_002428888, EEB16150
5.24E-48
74.63768
176.792 138
103
Th_d_00078892-RA
lysosomal alpha-mannosidase 432
gi|195377741|ref|XP_002047646.1|uncharacterized protein Dvir_GJ11812 [Drosophila virilis]gi|194154804|gb|EDW69988.1|uncharacterized protein Dvir_GJ11812 [Drosophila virilis] Diptera
gi|242016705|ref|XP_002428888.1|predicted protein [Pediculus humanus corporis]gi|212513656|gb|EEB16150.1|predicted protein [Pediculus humanus corporis]
gi|1108476517|emb|CRK95286.1|CLUMA_CG008644, isoform B [Clunio marinus] Diptera
CRK95286
6.19E-12
62.66667
69.3218 75 47
Th_d_00057287-RA
beta-glucuronidase-like isoform X1 634
gi|1330889853|gb|PNF22051.1|hypothetical protein B7P43_G09739 [Cryptotermes secundus]
Blattodea
PNF22051
9.67E-83
78.16092
253.832 174 136
124
Table 3.5. Continued.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00033402-RA
beta-glucuronidase isoform X3 1014
gi|194756422|ref|XP_001960477.1|uncharacterized protein Dana_GF11493 [Drosophila ananassae]gi|190621775|gb|EDV37299.1|uncharacterized protein Dana_GF11493 [Drosophila ananassae] Diptera
gi|1227980746|ref|XP_021921963.1|uncharacterized protein KIAA0513 isoform X3 [Zootermopsis nevadensis]
Blattodea
XP_021921963
1.5E-115
93.25843
341.658 178 166
138
Table 3.6. Continued.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Th_d_00073223-RA Maltase 1 927
gi|1339067252|ref|XP_023720702.1|uncharacterized protein KIAA0513 [Cryptotermes secundus]gi|1330886365|gb|PNF20093.1|hypothetical protein B7P43_G05254 [Cryptotermes secundus]gi|1330886366|gb|PNF20094.1|hypothetical protein B7P43_G05254 [Cryptotermes secundus]
gi|1339067252|ref|XP_023720702.1|uncharacterized protein KIAA0513 [Cryptotermes secundus]gi|1330886365|gb|PNF20093.1|hypothetical protein B7P43_G05254 [Cryptotermes secundus]gi|1330886366|gb|PNF20094.1|hypothetical protein B7P43_G05254 [Cryptotermes secundus]
Table 3.10. Lytic polysaccharide monooxygenases (LPMOs) in Thermobia domestica: Coding sequences in T. domestica genome encoding for LPMOs and their blast description.
Table 3.11. Endoglucanases in Ctenolepisma longicaudata: Coding sequences in C. longicaudata genome encoding for endoglucanases and their blast description.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00020160-RA
endoglucanase 13-like
513 gi|1330895262|gb|PNF24409.1|hypothetical protein B7P43_G09674, partial [Cryptotermes secundus]
gi|1228018667|ref|XP_021941324.1|uncharacterized protein LOC110840536 [Zootermopsis nevadensis] Blattodea
XP_021941324
3.1E-100
63.10976
310.457 328
207
176
Table 3.11. Continued.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order Hit ACC E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00013083-RA
Endoglucanase E-4 precursor, putative 1834
gi|1339056265|ref|XP_023716596.1|uncharacterized protein LOC111869358 [Cryptotermes secundus]gi|1339056267|ref|XP_023716597.1|uncharacterized protein LOC111869358 [Cryptotermes secundus]gi|1330895261|gb|PNF24408.1|hypothetical protein B7P43_G09674 [Cryptotermes secundus]
Blattodea
XP_023716596, XP_023716597, PNF24408
1.42E-40
78.47222
159.844 144
113
Lep_00013082-RA
endoglucanase E-4-like 1314
gi|646711640|gb|KDR16731.1|Endoglucanase F [Zootermopsis nevadensis]
Table 3.12. Glucosidases in Ctenolepisma longicaudata: Coding sequences in C. longicaudata genome encoding for glucosidases and their blast description.
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 957
gi|303324839|pdb|3AHZ|AChain A, Crystal Structure Of Beta-Glucosidase From Termite Neotermes Koshunensis In Complex With Trisgi|393715252|pdb|3VIF|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Gluconolactonegi|393715253|pdb|3VIG|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With 1-deoxynojirimycingi|393715254|pdb|3VIH|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Glycerolgi|393715255|pdb|3VII|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Bis-tris
Blattodea
3AHZ_A, 3VIF_A, 3VIG_A, 3VIH_A, 3VII_A
1.6E-122
75.52448
365.925 286 216
189
Table 3.12. Continued.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order
Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00036380-RA
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 1194
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 1844
gi|303324839|pdb|3AHZ|AChain A, Crystal Structure Of Beta-Glucosidase From Termite Neotermes Koshunensis In Complex With Trisgi|393715252|pdb|3VIF|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Gluconolactonegi|393715253|pdb|3VIG|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With 1-deoxynojirimycingi|393715254|pdb|3VIH|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Glycerolgi|393715255|pdb|3VII|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Bis-tris
Blattodea
3AHZ_A, 3VIF_A, 3VIG_A, 3VIH_A, 3VII_A
9E-147
71.88498
368.622 313 225
191
Table 3.12. Continued.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order
Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00004873-RA
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 375
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 843
gi|303324839|pdb|3AHZ|AChain A, Crystal Structure Of Beta-Glucosidase From Termite Neotermes Koshunensis In Complex With Trisgi|393715252|pdb|3VIF|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Gluconolactonegi|393715253|pdb|3VIG|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With 1-deoxynojirimycingi|393715254|pdb|3VIH|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Glycerolgi|393715255|pdb|3VII|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Bis-tris
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 291
gi|393715257|pdb|3VIK|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Cellobiosegi|393715258|pdb|3VIL|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Salicin
Blattodea
3VIK_A, 3VIL_A
5.81E-37
83.90805
135.191 87 73
195
Table 3.12. Continued.
Sequence name
Sequence desc. Sequence length
Hit desc. Order Hit ACC E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00004127-RA
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 837
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 1032
gi|303324839|pdb|3AHZ|AChain A, Crystal Structure Of Beta-Glucosidase From Termite Neotermes Koshunensis In Complex With Trisgi|393715252|pdb|3VIF|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Gluconolactonegi|393715253|pdb|3VIG|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With 1-deoxynojirimycingi|393715254|pdb|3VIH|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Glycerolgi|393715255|pdb|3VII|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Bis-tris
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 792
gi|303324839|pdb|3AHZ|AChain A, Crystal Structure Of Beta-Glucosidase From Termite Neotermes Koshunensis In Complex With Trisgi|393715252|pdb|3VIF|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Gluconolactonegi|393715253|pdb|3VIG|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With 1-deoxynojirimycingi|393715254|pdb|3VIH|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Glycerolgi|393715255|pdb|3VII|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Bis-tris
AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With A New Glucopyranosidic Product 954
gi|303324839|pdb|3AHZ|AChain A, Crystal Structure Of Beta-Glucosidase From Termite Neotermes Koshunensis In Complex With Trisgi|393715252|pdb|3VIF|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Gluconolactonegi|393715253|pdb|3VIG|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With 1-deoxynojirimycingi|393715254|pdb|3VIH|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Glycerolgi|393715255|pdb|3VII|AChain A, Crystal Structure Of Beta-glucosidase From Termite Neotermes Koshunensis In Complex With Bis-tris
uncharacterized family 31 glucosidase KIAA1161-like 186
gi|1228003699|ref|XP_021933735.1|uncharacterized family 31 glucosidase KIAA1161-like [Zootermopsis nevadensis]
Blattodea
XP_021933735
2.82E-22
83.05085
93.9745 59 49
Lep_00085182-RA
uncharacterized family 31 glucosidase KIAA1161 isoform X1
2409
gi|242004884|ref|XP_002423306.1|conserved hypothetical protein [Pediculus humanus corporis]gi|212506315|gb|EEB10568.1|conserved hypothetical protein [Pediculus humanus corporis]
Phthiraptera
XP_002423306, EEB10568 0
72.99383
707.983 648 473
Lep_00076013-RA
uncharacterized family 31 glucosidase KIAA1161-like 180
gi|1101361447|ref|XP_018913028.1|PREDICTED: uncharacterized family 31 glucosidase KIAA1161-like [Bemisia tabaci]
Hemiptera
XP_018913028
2.48E-20
83.01887
88.1965 53 44
207
Table 3.12. Continued.
Sequence name
Sequence desc. Sequence length
Hit desc. Order
Hit ACC E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00076014-RA
uncharacterized family 31 glucosidase KIAA1161-like 405
gi|1101398930|ref|XP_018910486.1|PREDICTED: uncharacterized family 31 glucosidase KIAA1161-like [Bemisia tabaci]
Hemiptera
XP_018910486
3.47E-19
80.95238
88.5817 63 51
Lep_00089518-RA
uncharacterized family 31 glucosidase KIAA1161-like isoform X1 1839
gi|1330911882|gb|PNF32421.1|hypothetical protein B7P43_G04891 [Cryptotermes secundus]
Blattodea
PNF32421
3.8E-172 60
509.22 585 351
Lep_00071777-RA
Uncharacterized family 31 glucosidase KIAA1161 2259
gi|1228003699|ref|XP_021933735.1|uncharacterized family 31 glucosidase KIAA1161-like [Zootermopsis nevadensis]
Blattodea
XP_021933735
2.5E-150
67.98144
458.373 431 293
Lep_00161546-RA
uncharacterized family 31 glucosidase KIAA1161-like 1098
gi|1067066097|ref|XP_018017064.1|PREDICTED: uncharacterized family 31 glucosidase KIAA1161-like [Hyalella azteca]
Crustacea
XP_018017064
3.56E-86
55.82656
277.715 369 206
Lep_00074517-RA
uncharacterized family 31 glucosidase KIAA1161 156
gi|636630780|gb|AIA09350.1|alpha-glucosidase family 31, partial [Periplaneta americana]
Blattodea
AIA09350
3.74E-14
81.25
70.0922 48 39
208
Table 3.12. Continued.
Sequence name
Sequence desc. Sequence length
Hit desc. Order
Hit ACC E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00042846-RA
neutral alpha-glucosidase AB 789
gi|1339041694|ref|XP_023710162.1|neutral alpha-glucosidase AB [Cryptotermes secundus]gi|1330933432|gb|PNF42738.1|Neutral alpha-glucosidase AB [Cryptotermes secundus]
Blattodea
XP_023710162, PNF42738
2.4E-54
70.45455
194.126 176 124
Lep_00097084-RA
Lysosomal alpha-glucosidase 717
gi|321476729|gb|EFX87689.1|hypothetical protein DAPPUDRAFT_312137 [Daphnia pulex]
Crustacea
EFX87689
1.87E-84
72.76786
274.633 224 163
Lep_00136184-RA
uncharacterized family 31 glucosidase KIAA1161-like 1527
gi|636630780|gb|AIA09350.1|alpha-glucosidase family 31, partial [Periplaneta americana]
Blattodea
AIA09350
2E-163
71.60194
481.871 412 295
Lep_00079073-RA
uncharacterized family 31 glucosidase KIAA1161-like 336
gi|1228003699|ref|XP_021933735.1|uncharacterized family 31 glucosidase KIAA1161-like [Zootermopsis nevadensis]
Blattodea
XP_021933735
2.34E-21
78.78788
93.5893 66 52
Lep_00079074-RA
uncharacterized family 31 glucosidase KIAA1161-like 315
gi|1330911882|gb|PNF32421.1|hypothetical protein B7P43_G04891 [Cryptotermes secundus]
gi|1330905640|gb|PNF29605.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905643|gb|PNF29608.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905644|gb|PNF29609.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]
Blattodea
PNF29605, PNF29608, PNF29609
3.67E-92
66.89189
291.197 296 198
Lep_00135198-RA
uncharacterized family 31 glucosidase KIAA1161-like 597
gi|646703149|gb|KDR11965.1|hypothetical protein L798_13618, partial [Zootermopsis nevadensis]
Blattodea
KDR11965
1.14E-67
71.42857
221.09 189 135
Lep_00136521-RA
uncharacterized family 31 glucosidase KIAA1161-like 666
gi|646703149|gb|KDR11965.1|hypothetical protein L798_13618, partial [Zootermopsis nevadensis]
Blattodea
KDR11965
2.69E-75
70.95238
241.891 210 149
Lep_00094746-RA
uncharacterized family 31 glucosidase KIAA1161-like 1476
gi|636630780|gb|AIA09350.1|alpha-glucosidase family 31, partial [Periplaneta americana]
Blattodea
AIA09350
1.7E-162
71.35922
479.174 412 294
211
Table 3.12. Continued.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order
Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00102111-RA
uncharacterized family 31 glucosidase KIAA1161-like 519
gi|646703149|gb|KDR11965.1|hypothetical protein L798_13618, partial [Zootermopsis nevadensis]
Blattodea
KDR11965
7.91E-49
80.17241
170.629 116 93
Lep_00054791-RA
lysosomal alpha-glucosidase-like 291
gi|1330905640|gb|PNF29605.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905643|gb|PNF29608.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905644|gb|PNF29609.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]
Blattodea
PNF29605, PNF29608, PNF29609
4.26E-44
89.77273
153.68 88 79
Lep_00054790-RA
lysosomal alpha-glucosidase-like 957
gi|1330905640|gb|PNF29605.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905643|gb|PNF29608.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]gi|1330905644|gb|PNF29609.1|hypothetical protein B7P43_G01635 [Cryptotermes secundus]
gi|1227991790|ref|XP_021927674.1|neutral alpha-glucosidase AB isoform X2 [Zootermopsis nevadensis]
Blattodea
XP_021927674
2.41E-35
83.52941
137.502 85 71
Lep_00011466-RA
lysosomal alpha-glucosidase-like 324
gi|1022768805|gb|KZS13426.1|Uncharacterized protein APZ42_021387 [Daphnia magna]
Crustacea
KZS13426
7.46E-17
76.5625
80.4925 64 49
213
Table 3.13. β-1,3-glucanases in Ctenolepisma longicaudata: Coding sequences in C. longicaudata genome encoding for β-1,3-glucanases and their blast description.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order Hit ACC E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00027153-RA
beta-1,3-glucan-binding protein precursor 7782
gi|1339068387|ref|XP_023721291.1|uncharacterized protein LOC111872033 isoform X1 [Cryptotermes secundus]
Table 3.15. Glucuronidases in Ctenolepisma longicaudata: Coding sequences in C. longicaudata genome encoding for glucuronidases and their blast description.
Sequence name
Sequence desc.
Sequence length
Hit desc. Order Hit ACC
E-Value
Similarity
Bit-Score
Alignment length
Positives
Lep_00101143-RA
beta-glucuronidase-like isoform X1 414
gi|1330907784|gb|PNF30346.1|hypothetical protein B7P43_G13405 [Cryptotermes secundus]
gi|968019329|ref|XP_015011863.1|uncharacterized protein Dere_GG20922, isoform C [Drosophila erecta]gi|945202794|gb|KQS62122.1|uncharacterized protein Dere_GG20922, isoform C [Drosophila erecta]
Table 3.18. Galactosidases in Ctenolepisma longicaudata: Coding sequences in C. longicaudata genome encoding for galactosidases and their blast description.
gi|1080052826|ref|XP_018567975.1|lactase-like protein [Anoplophora glabripennis]
Coleoptera
XP_018567975
1.85E-35
62.73292
135.576 161 101
296
Table 3.21. Lytic polysaccharide monooxygenases (LPMOs) in Ctenolepisma longicaudata: Coding sequences in C. longicaudata genome encoding for LPMOs and their blast description.
gi|1316145279|ref|XP_023217685.1|uncharacterized protein LOC111620072 [Centruroides sculpturatus]gi|1316145289|ref|XP_023217690.1|uncharacterized protein LOC111620076 [Centruroides sculpturatus]
gi|759036658|ref|XP_011345707.1|PREDICTED: uncharacterized protein LOC105284120 [Ooceraea biroi]gi|607367294|gb|EZA61441.1|hypothetical protein X777_07774 [Ooceraea biroi]
Hymenoptera
XP_011345707, EZA61441
3.24E-48
71.97452
165.236 157 113
Lep_00045172-RA
Lytic polysaccharide monooxygenase 357
gi|759036658|ref|XP_011345707.1|PREDICTED: uncharacterized protein LOC105284120 [Ooceraea biroi]gi|607367294|gb|EZA61441.1|hypothetical protein X777_07774 [Ooceraea biroi]
Hymenoptera
XP_011345707, EZA61441
4.63E-35
66.08696
125.561 115 76
Lep_00099441-RA
Lytic polysaccharide monooxygenase 724
gi|1009534315|ref|XP_015904140.1|uncharacterized protein LOC107436837 [Parasteatoda tepidariorum]
gi|1238881740|ref|XP_022253834.1|uncharacterized protein LOC106469570 isoform X1 [Limulus polyphemus]gi|1238881742|ref|XP_022253835.1|uncharacterized protein LOC106469570 isoform X1 [Limulus polyphemus]
Arthropoda
XP_022253834, XP_022253835
6.63E-60
55.55556
204.912 288 160
Lep_00006589-RA
Lytic polysaccharide monooxygenase 335
gi|1009534315|ref|XP_015904140.1|uncharacterized protein LOC107436837 [Parasteatoda tepidariorum]
Arachnida
XP_015904140
1.22E-15
65.82278
75.485 79 52
309
Table 3.22. Number of predicted endogenously produced endoglucanases, β-glucosidases and β-glucuronidases in genomes of insects (highlighted indicates our work). Data on Cryptocercus punctulatus and Reticulitermes flavipes were collected from identical protein groups database of NCBI.
Insect species Endoglucanase β-glucosidase β-glucuronidase
Blattodea
Blatella germanica 2 0 4
Cryptocercus punctulatus 0 1 0
Reticulitermes flavipes 5 1 0
Zootermopsis nevadensis 5 2 4
Zygentoma
Thermobia domestica 85 19 39
Ctenolepisma longicaudata 69 22 30
Coleoptera
Tribolium castaneum 1 0 0
Dendroctonus ponderosae 10 5 3
Lepidoptera
Bombyx mori 0 4 1
Manduca sexta 1 9 10
Plutella xylostella 2 14 1
Diptera
Drosophila melanogaster 1 3 7
Bactrocera cucurbitae 0 0 8
310
Table 3.22. Continued.
Insect species Endoglucanase β-glucosidase β-glucuronidase
Hemiptera
Acyrthosiphon pisum 4 20 4
Nilaparvta lugens 7 13 1
Hymenoptera
Apis dorsata 1 0 3
Megachile rotundata 3 2 4
Anoplura
Pediculus humanus 1 1 1
311
Figure 3.1. Annotation of Thermobia domestica coding sequences: Number and relative percentage of T. domestica coding sequences with blast hits, with no blast hits, annotated and mapped.
312
Figure 3.2. Top-hit species distribution for Thermobia domestica: Number of blast hits matching with highest identity to different species.
313
Figure 3.3. Enzyme Code distribution in Thermobia domestica: Number of coding sequences of T. domestica encoding for enzymes belonging to different enzyme commission classes (EC).
314
Figure 3.4. Enzyme Code distribution of hydrolases in Thermobia domestica: Number of coding sequences of T. domestica encoding for enzymes belonging to different enzyme commission (EC) subclasses of hydrolases.
315
Figure 3.5. Glycoside hydrolases (GH) and lytic polysaccharide monoxygenases (LPMOs) in Thermobia domestica: Distribution of enzymes encoding for different glycoside hydrolases and LPMOs in T. domestica.
316
Figure 3.6. Annotation of Ctenolepisma longicaudata coding sequences: Number and percentage of C. longicaudata coding sequences with blast hits, with no blast hits, annotated and mapped.
317
Figure 3.7. Top-hit species distribution for Ctenolepisma longicaudata: Number of blast hits with highest identity to different species.
318
Figure 3.8. Enzyme Code distribution in Ctenolepisma longicaudata: Number of coding sequences of C. longicaudata encoding for enzymes belonging to different enzyme commission classes (EC).
319
Figure 3.9. Enzyme Code distribution of hydrolases in Ctenolepisma longicaudata: Number of coding sequences of C. longicaudata encoding for enzymes belonging to different enzyme commission (EC) subclasses of hydrolases.
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Figure 3.10. Glycoside hydrolases (GH) and lytic polysaccharide monoxygenases (LPMOs) in Ctenolepisma longicaudata: Distribution of enzymes encoding belong to different glycoside hydrolases and LPMOs in C. longicaudata.
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Chapter 4
Differential expression of cellulose degrading enzyme genes in Thermobia domestica
and Ctenolepisma longicaudata in response to diets of different cellulosic content
322
Pothula, R.; Johnson, B.R.; Klingeman, W.E.; Huff, M.; Staton, M.E. and J.L. Jurat-Fuentes.
(2018).
My contributions included: (1) planning and performing experiments, (2) data collection
and analysis, (3) writing the manuscript and making figures. Brian R. Johnson, Matthew
Huff and Margaret Staton helped with 2 and Juan Luis Jurat-Fuentes assisted with (1, 2 and
3).
Abstract
Members of Zygentoma have been characterized as having the highest relative
cellulolytic activity compared to traditional model insects used for biofuel research such as
termites, cockroaches and beetles (Chapter 2). However, not much-information is available
on cellulolytic genes in these non-model organisms. In the present work, our goal was to
study the differential expression of cellulase genes in the foregut and other body tissues
when Thermobia domestica and Ctenolepisma longicaudata were fed on four diets with
varying degree of cellulosic content. Using an RNASeq approach, differential gene
expression analysis of both species revealed that cellulase gene expression is primarily
driven by type of tissue rather than diet. However, within each tissue of T. domestica and C.
longicaudata, a higher number of plant cell wall degrading enzymes (PCWDEs) and lytic
polysaccharide monoxygenases were significantly up-regulated in the paper diet
treatment, which is highly cellulosic, compared to all other tested diets. The annotation of
differentially expressed PCWDE genes revealed highest identity to insect homologs, which
suggests the potential conservation of PCWDEs through evolution and the ancient origin of
cellulases in insects. Overall, our research contributes to increasing the amount of
323
information available on functional PCWDE genes and lytic polysaccharide monoxygenases
(LPMOs) from a primitive hexapod group with potential for industrial biofuel applications.
Introduction
Cellulases are a group of enzymes that completely digest plant cellulose into
glucose, which in the biofuel industry can be fermented by yeast to generate bioethanol.
Enzymatic activities within cellulases include endoglucanase, which cleaves the cellulose
chain internally at random, exoglucanase that cleaves the cellulose chain at the ends
releasing cellobiose, and β-glucosidase that degrades cellobiose into glucose units
(Watanabe and Tokuda, 2010). These plant cell wall degrading enzymes (PCWDEs) have
been traditionally described from microorganisms, yet in the last decade or so insects have
also been considered a prospecting resource for endogenously produced PCWDEs,
including cellulases, hemicellulases and pectinases (Calderón-Cortés et al., 2012; Watanabe
and Tokuda, 2010). Endoglucanases and β-glucosidases are commonly found in insects, yet
to date insect exoglucanases have not been reported (Martin, 1983; Scrivener and Slaytor,
1994). This may be due to the function of exoglucanases in insects being compensated by
the presence of a higher number of endoglucanases with dual endo/exo activity (Scrivener
and Slaytor, 1994), and/or physical processing by mandibles and proventriculus and/or a
long digestive tube that allows for increased length of digestion in the gut (Calderón-Cortés
et al., 2012; Watanabe and Tokuda, 2010). Hemicellulases and pectinases digest
hemicellulose and pectin polysaccharides, respectively, which are interlocked with
cellulose fibers in the plant cell wall (Gilbert, 2010). Insects belonging to 16 taxonomic
orders were reported to have endogenous production of one or more of PCWDEs
324
(Calderón-Cortés et al., 2012). However, molecular evidence confirming the presence of
PCWDE genes including endoglucanases belonging to glycoside hydrolase family (GH) 9
and 45 , β-glucosidases of GH 5, hemicellulases such as xyloglucanases of GH 5 and GH 11,
β-1,3-glucanases of GH 16 and pectinases of GH 28, has only been obtained from insects
belonging to only 8 taxonomic orders (Calderón-Cortés et al., 2012).
Whole transcriptome shotgun sequencing, or RNA-Seq, is a next generation
sequencing technique allowing for quantitative determination of total transcripts present
as a proxy for the level of expression of the corresponding gene in a cell, tissue or whole
organism (Wang et al., 2009). Unlike microarrays and traditional sequencing technologies,
RNA-Seq can be conveniently used to find functional genes, such as cellulases, in non-model
organisms (Shelomi et al., 2014; Vera et al., 2008). Additionally, RNA-Seq studies can
identify differentially expressed genes when comparing between different tissues and/or
under distinct conditions.
Members of Zygentoma have been characterized as having the highest relative
cellulolytic activity against carboxymethylcellulose compared to traditional model insects
used for biofuel research such as termites, cockroaches and beetles (Chapter 2). However,
there is a lack of information on the molecular characterization of cellulolytic activity in
these non-model organisms. Previous work detected endoglucanase, β-glucosidase,
xylanase, pectinase, amylase, maltase, sucrase and lactase activities in foregut fluids from
Thermobia domestica and Ctenolepisma longicaudatathrough biochemical tests (Zinkler and
Götze, 1987; Chapter 2). In addition to cellulase and xylanase activities, investigation of the
digestive proteome of T. domestica revealed the production of lytic polysaccharide
325
monoxygenases (LPMOs), which are enzymes that form nicks in cellulose fibers thereby
making them more accessible to cellulases (Sabbadin et al., 2018).
In the present work, our goal was to find cellulase genes that are responsible for the
high relative cellulolytic activity in T. domestica and C. longicaudata compared to other
insects. In addition, we used RNAseq to study their differential expression in foregut and
rest of the body samples when T. domestica and C. longicaudata were fed on four diets with
varying degree of cellulosic content. Differential gene expression analysis of both species
revealed that cellulase gene expression is primarily driven by type of tissue rather than
diet. However, within each tissue of T. domestica and C. longicaudata, higher number of
PCWDEs were significantly up-regulated in insects fed on the paper diet treatment, which
is highly cellulosic compared to all other tested diets. Additionally, more LPMOs were up-
regulated in the foregut tissue of paper-fed T. domestica than other diets, yet LPMO up-
regulation was not as prominent in C. longicaudata, which may help explain higher
cellulolytic activity in T. domestica compared to C. longicaudata. The annotation of
differentially expressed PCWDE genes revealed highest identity to insect homologs, which
suggests the potential conservation of PCWDEs through evolution. Overall, our research
contributes to increasing the amount of information available on functional PCWDE genes
and LPMOs from a primitive hexapod group with potential for industrial biofuel
applications.
326
Materials and Methods
Insect rearing
Adult silverfish (Ctenolepisma longicaudata) and firebrat (Thermobia domestica)
were used in this study. Several batches of nymphs and adults of C. longicaudata were
hand-collected by sweeping into collection containers or collected into lid-less plastic
transcripts encoding for LPMOs were up-regulated in the foregut tissue of T. domestica fed
on CMC compared to protein and switchgrass diets (Table 4.2). However, LPMOs were not
differentially expressed in the foregut tissue of T. domestica fed on switchgrass compared
to protein diet (Table 4.2).
Unlike observations in the foregut tissue, cellulase gene expression in the rest of the
body sample was increased as cellulosic content increased in the diet. The most striking
difference was detected when feeding T. domestica on paper compared to protein diet,
which resulted in up-regulation of 15 endoglucanase genes (Table 4.3). The rest of the body
sample of T. domestica fed on paper diet had 14 endoglucanases that were up-regulated
compared to T. domestica fed switchgrass, and 9 endoglucanases, one β-glucosidase, and
one mannanase significantly up-regulated compared to a CMC diet. However, CMC and
switchgrass diets resulted in significant up-regulation of only two endoglucanases
compared to protein diet (Table 4.3).
In contrast to foregut tissue, the differential gene expression analyses of the rest of
the body sample of T. domestica fed on different diets revealed that very few LPMOs were
differentially expressed (Table 4.4). Feeding T. domestica on paper and switchgrass diets
did not result in differential expression of LPMOs compared to protein diet. Nevertheless,
CMC diet resulted in up-regulation of one and three LPMOs compared to protein and paper
diets, respectively (Table 4.4). Additionally, feeding on a paper diet resulted in up-
regulation of five transcripts encoding for LPMOs compared to switchgrass diet in rest of
the body sample of T. domestica (Table 4.4). Among all significantly differentially expressed
genes in different pair-wise comparisons, seven endoglucanases and seven LPMOs were
331
commonly expressed in both foregut and rest of the body samples. Overall, differential
gene expression analysis detected 35 significantly up-regulated cellulase genes in T.
domestica fed on different diets (Table 4.9). In the same analyses, 26 and 9 transcripts
encoding for LPMOs were significantly differentially expressed in different pair-wise
comparisons among treatments in foregut and rest of the body samples, respectively (Table
4.2 and 4.4).
Annotation of differentially expressed PCWDE genes in T. domestica
Among the 35 genes differentially expressed, endoglucanases (26 coding sequences)
were the most abundant cellulases, 22 of which matched endoglucanases of insect origin.
Among the other four endoglucanases, two were most similar to molluscan cellulases, one
matched to a copepod (Eurytemora affinis) cellulase and another was most identical to an
enzyme from a cnidarian (Orbicella faveolata) (Table 4.9). In addition to endoglucanases,
cellulases differentially expressed included four β-galactosidases matching to different
organisms such as sawfly (Cephus cinctus), water flea (Daphnia pulex), fish (Austrofundulus
limnaeus) and opossum (Monodelphis domestica); two β-glucuronidases matching to
termites (Zootermopsis nevadensis and Neotermes koshunensis); two mannanases, one
matching to a springtail (Orchesella cincta) and another matching to freshwater crayfish
(Cherax quadricarinatus); and one transcript of a β-glucosidase in GH 31 matching to the
cockroach, Periplaneta americana (Table 4.9).
Differential cellulase gene expression analysis in C. longicaudata
Similar to results from T. domestica, differential gene expression analysis in C.
longicaudata foregut tissue fed on CMC diet did not result in detection of differential
332
expression of any cellulase genes compared to the insects fed on protein diet (Table 4.5).
However, in contrast to T. domestica, feeding C. longicaudata on switchgrass resulted in up-
regulation of one endoglucanase (GH 9), one β-galactosidase, and two β-glucuronidases in
the foregut tissue compared to protein diet (Table 4.5). Additionally, 13 endoglucanases
were significantly up-regulated in the foregut tissue of C. longicaudata fed on paper diet
compared to protein diet. Similarly, 12 genes encoding for endoglucases were up-regulated
in C. longicaudata foregut tissue fed on paper compared to CMC diet and one mannosidase
encoding gene was up-regulated in CMC diet fed C. longicaudata compared to protein diet
(Table 4.5). Furthermore, feeding C. longicaudata on paper resulted in up-regulation of five
endoglucanase encoding genes and one β-1,3-glucanase compared to the switchgrass
treatment (Table 4.5).
Similar to cellulases, differential gene expression analysis of LPMO genes revealed
that foregut tissue of C. longicaudata fed on CMC did not have any differentially expressed
LPMO genes compared to that fed on protein diet. However, 11 and three LPMO encoding
genes were significantly up-regulated in the foregut tissue of C. longicaudata fed on paper
and switchgrass, respectively, when compared to protein diet (Table 4.6). Feeding of C.
longicaudata on CMC and switchgrass resulted in up-regulation of only one LPMO gene in
the foregut tissue compared to feeding on paper and CMC, respectively (Table 4.6).
Unlike in foregut tissue, differential gene expression analysis on the rest of the body
sample of C. longicaudata revealed that feeding C. longicaudata on CMC resulted in
differential cellulase gene expression compared to protein diet. One glucosidase was up-
regulated in the rest of the body sample of C. longicaudata fed on CMC compared to protein
333
diet, while two endoglucanase encoding genes, two β-galactosidases and nine glucosidases
were up-regulated in the reciprocal comparison (Table 4.7). Similarly, seven genes
encoding for endoglucanases and one glucosidase were up-regulated on paper diet
compared to protein. When comparing protein to paper diet, two endoglucanases, two
glucosidases, and one galactosidase were up-regulated (Table 4.7). Likewise, four
endoglucanase encoding genes, three β-glucosidases, one β-1,3-glucanase, and one gene
encoding for an enzyme in GH 65 were up-regulated in C. longicaudata fed on switchgrass
compared to protein. In the reciprocal comparison, we detected four glucosidases, two
endoglucanases, and one β-galactosidase as up-regulated (Table 4.7). Feeding C.
longicaudata on switchgrass up-regulated the expression of 15 glucosidases, nine
endoglucanases, five β-glucuronidases, one β-1,3-glucanase, one β-galactosidase, one β-1,6-
glucanase, and one GH 65 enzyme in the rest of the body sample when compared to feeding
on CMC. In contrast, CMC up-regulated the expression of only three endoglucanases
compared to switchgrass. However, in contrast to other pair-wise diet comparisons, C.
longicaudata fed a paper diet up-regulated all cellulase encoding genes, 16 endoglucanases,
two β-glucosidases, and one β-1,6-glucanase compared to feeding on CMC (Table 4.7).
Additionally, 16 endoglucanases were up-regulated in rest of the body sample of paper fed
C. longicaudata compared to feeding on switchgrass. In the reciprocal comparison, only one
mannosidase, one glucosidase and one β-galactosidase were up-regulated in switchgrass
fed C. longicaudata rest of the body sample compared to paper diet (Table 4.7).
LPMOs were not significantly differentially expressed in C. longicaudata rest of the
body sample fed on CMC and paper compared to protein diet. However, six LPMO encoding
334
genes were significantly up-regulated in paper diet compared to CMC (Table 4.8). Similarly,
the expression of 18, six and five LPMOs were significantly up-regulated in C. longicaudata
rest of the body sample in insects fed on switchgrass compared to CMC, protein and paper
diets, respectively (Table 4.8). Overall, 16 genes encoding cellulases and six LPMO encoding
genes were commonly expressed in both foregut and rest of the body samples of C.
longicaudata.
Annotation of differentially expressed PCWDE genes in C. longicaudata
Annotation of all significantly differentially expressed cellulase genes across all
fedding treatments in C. longicaudata yielded 70 genes encoding for cellulases. Similar to T.
domestica, the majority (31 sequences) of the differentially expressed cellulase genes in C.
longicaudata encoded for β-1,4-endoglucanases, 30 of which matched to proteins of insect
origin and one was most similar to a sea anemone (Nematostella vectensis) (Table 4.10).
After endoglucanases, the most common differentially expressed cellulases were β-
glucosidases (18 genes), 13 of which matched to insect enzymes, while 3 were most similar
to molluscans, one was most similar to a fish (Acanthochromis polyacanthus), and another
was most similar to the crown-of-thorns starfish (Acanthaster planci) (Table 4.10). In
addition to β-1,4-endoglucanases, two sequences encoding for β-1,6-glucanases, which
were most similar to molluscan genes, and two β-1,3-glucanases, one similar to a
coleopteran (Dendroctonus ponderosae) and one most similar to a crustacean (Daphnia
pulex) gene, were found. Additionally, one mannanase most similar to a crustacean
(Daphnia magna) genes; six α-glucosidases which matched to other insect homologs; six β-
glucuronidases matching to insect or other arthropod genes; and five β-galactosidases
335
matching to insects were found (Table 4.10). Of the 84 LPMO encoding sequences
annotated in the C. longicaudata genome, only 15 and 25 LPMO encoding sequences were
significantly differentially expressed in foregut and rest of the body samples across
different pair-wise treatment comparisons.
Discussion
In our previous work (Chapter 2), we found Zygentoma displayed highest relative
cellulase activity compared to other model insects for biofuel research such as termites,
cockroaches and beetles. In addition, digestive fluids from both T. domestica and C.
longicaudata were found to have endoglucanase, xylanase, β-glucosidase and pectinase
activities, which are responsible for efficient digestion of cellulose into glucose.
Additionally, higher CMCase activity was found in foregut compared to other regions of the
digestive system in both species. In the present work, we investigated the endogenous
PCWDEs and their differential expression in T. domestica and C. longicaudata foregut and
rest of the body samples in response to diets with varying cellulose content through RNA-
Seq.
Differential expression of cellulase genes in foregut and rest of the body samples of T.
domestica and C. longicaudata fed on protein, paper, CMC and switchgrass diets was
primarily driven by tissue type rather than diet (Fig. 4.1 and 4.2). Thus, in most cases
cellulase gene expression was localized to a particular tissue (foregut versus rest of the
body), independently of the diet. However, almost all of the up-regulated genes in foregut
tissue were encoding for endoglucanases, while the majority of the up-regulated genes in
the rest of the body sample encoded for β-glucosidases. This observation indicates the
336
compartmentalization of cellulose digestion in both T. domestica and C. longicaudata, as
proposed for other insects (Fischer et al., 2013) (Fig. 4.1 and 4.2 & Table 4.9 and 4.10).
According to this model, the long cellulose chain is broken down into smaller pieces by
endoglucanases up-regulated in the foregut tissue, which is followed by further digestion of
intermediate products into glucose by β-glucosidases, which were up-regulated in the rest
of the body samples that include midgut and hindgut tissues.
Similar to cellulases, differential LPMO gene expression in T. domestica and C.
longicaudata was also mostly driven by the type of tissue rather than diet, although
differences in expression were detected also when comparing between some diets (Fig. 4.3
and 4.5). Nevertheless, almost all significantly differentially expressed LPMOs were up-
regulated in foregut tissue of T. domestica and C. longicaudata compared to the rest of the
body samples (Figs. 4.4 and 4.6). The up-regulation of LPMOs in foregut tissue is in
agreement with the function of LPMOs in attacking long cellulose polymers to form nicks in
cellulose polymers and make them more accessible to cellulases (Villares et al., 2017).
Although cellulase gene expression was primarily driven by tissue type, within each
tissue the cellulase gene expression was regulated by type of diet. Differential expression of
cellulase genes among different pair-wise treatment combinations within the foregut tissue
revealed that cellulase encoding genes were up-regulated in T. domestica fed paper
compared to diets with protein, switchgrass and CMC (Table 4.1). This result indicates a
correlation between cellulase gene up-regulation and highly cellulosic paper diet.
Compared to foregut tissue, the differential expression of cellulases in the rest of the body
was more firmly correlated with type of diet. For example, more PCWDEs were up-
337
regulated in the rest of the body sample of T. domestica fed on paper compared to other
diets (Table 4.3), which indicates the more recalcitrant nature of cellulose present in the
paper compared to other diets.
Similarly, more LPMOs were up-regulated in foregut tissue of T. domestica fed on
paper compared to all other diets (Table 4.2). This result also indicates the need for
production of more enzymes to digest recalcitrant paper diet. Additionally, LPMOs were
also up-regulated T. domestica fed CMC compared to protein and switchgrass diets, and no
LPMOs were differentially expressed between T. domestica fed protein and switchgrass
(Table 4.2). These observations may be explained by the protein and switchgrass diets
being a mixture of carbohydrate and protein, whereas the CMC diet is composed of only
carbohydrate whereby insects may need to consume and digest more CMC to meet their
energy demands. Similar up-regulation of LPMOs was reported in gut of T. domestica fed on
avicel versus less cellulosic diets (Sabbadin et al., 2018). Compared to foregut tissue, very
few LPMOs were significantly up-regulated in different pair-wise treatment comparisons of
the rest of the body sample (Table 4.4), which affirms the need for LPMO production within
foregut tissue versus other regions of the digestive system.
Unlike in T. domestica, cellulase gene expression in C. longicaudata foregut tissue
was correlated with type of diet. Among all pair-wise treatment combinations, more
PCWDEs were up-regulated in the foregut tissue of C. longicaudata fed on paper compared
to other diets (Table 4.5), which indicates the up-regulation of cellulase genes in response
to the most recalcitrant form of cellulose among the tested diets. Similarly, switchgrass diet
also resulted in up-regulated expression of a few cellulases compared to protein diet (Table
338
4.5), which again may be related to the more recalcitrant nature of switchgrass versus a
protein diet. In contrast to T. domestica and foregut tissue of C. longicaudata, the cellulase
gene expression in the rest of the body of C. longicaudata was regulated by both diets
within a pair-wise treatment comparison (Table 4.7). This observation may indicate that
cellulase gene expression in the rest of the body sample, which includes midgut and
hindgut, is controlled by the type of diet. Conversely, very few LPMOs were up-regulated in
foregut tissue of C. longicaudata (Tables 4.2 and 4.6), which could potentially help explain
lower relative cellulolytic activity of C. longicaudata compared to T. domestica (Chapter 2).
Overall, the annotation of significantly differentially expressed cellulase genes
identified 35 and 70 coding sequences encoding for cellulases in T. domestica and C.
longicaudata, respectively, across tissues and treatments (Table 4.9 and 4.10). Both T.
domestica and C. longicaudata were found expressing numerous endoglucanases and β-
glucosidases, which are considered as the main cellulase complex in insects for breakdown
of complex cellulose into glucose (Calderón-Cortés et al., 2012). Additionally, T. domestica
and C. longicaudata express 35 and 40 LPMOs, respectively, which probably are involved in
the higher cellulolytic activity in this group compared to other insects (Chapter 2).
However, C. longicaudata was found to express a higher number and also a more diverse
pool of PCWDEs and LPMOs compared to T. domestica. In contrast, T. domestica was found
to display higher endoglucanase, xylanase and pectinase activities than C. longicaudata
(Chapter 2). The higher activity in T. domestica with fewer enzyme genes expressed may be
explained by the correlation of type of diet and the expression of LPMOs in foregut tissue,
which was more prominent in T. domestica.
339
Most of the annotated PCWDEs in these Zygentoma species matched with highest
identity to proteins from termites and cockroaches, which may be indicative of close
evolutionary relationships between these groups. Moreover, some of the PCWDEs in T.
domestica and C. longicaudata were most identical to the most primitive hexapod groups,
such as Collembola (Orchesella cincta), or to highly evolved insect groups such as
hymenopterans, which may suggest the conservation of PCWDEs in insects through
evolution rather than frequent horizontal transfer from microorganisms (Calderón-Cortés
et al., 2012). However, a considerable number of PCWDEs matched to organisms from
other phyla, emphasizing the need for in-depth molecular characterization of PCWDEs in
all insect groups to shed insight on the evolution of cellulases in insects. Overall, our
research provides additional information on functional PCWDEs and LPMOs in T. domestica
and C. longicaudata as two representative members of a primitive hexapod group with high
relative cellulase activity.
340
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Appendix 4
347
Table 4.1. Effect of diet on plant cell wall degrading enzyme (PCWDE) gene expression in
foregut tissue of Thermobia domestica. Differentially expressed PCWDE genes in different
pair-wise treatment comparisons of foregut tissue of T. domestica fed on carboxymethyl
cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Enzyme Up-regulated diet Padj value
CMC vs Protein
Coding sequence
Th_d_00035294-RA hydrolase family 9 Protein 0.0003
Th_d_00006652-RA β-galactosidase Protein 0.0003
Th_d_00006654-RA β-galactosidase Protein 0.03
Th_d_00006653-RA β galactosidase Protein 0.01
Paper vs Protein
Coding sequence
Th_d_00001122-RA β-galactosidase-1 3 Paper 0.02
Th_d_00093510-RA hydrolase family 9 Paper 0.03
Th_d_00048538-RA
uncharacterized family
31 glucosidase
KIAA1161-like
Paper 0.005
Switchgrass vs
Protein
Coding sequence
Th_d_00000352-RA hydrolase family 9 Protein <0.001
Th_d_00046715-RA hydrolase family 9 Protein 0.02
Th_d_00028499-RA hydrolase family 9 Protein 0.0001
Th_d_00000351-RA endo- β-1,4-glucanase Protein 0.001
Th_d_00036630-RA Man5-K Protein 0.02
Th_d_00006653-RA β-galactosidase Protein 0.04
Th_d_00006652-RA β-galactosidase Protein 0.03
CMC vs Paper
Coding sequence
Th_d_00031500-RA Endoglucanase Paper 0.03
Switchgrass vs
Paper
Coding sequence
Th_d_00001122-RA β-galactosidase-1 3 Paper 0.05
Th_d_00071154-RA hydrolase family 9 Paper 0.03
Th_d_00093510-RA hydrolase family 9 Paper 0.001
Th_d_00061520-RA hydrolase family 9 Paper 0.02
348
Table 4.1. Continued.
Diets tested Enzyme Up-regulated diet Padj value
Th_d_00005705-RA hydrolase family 9 Paper 0.001
Th_d_00018098-RA β-glucuronidase-like Paper 0.04
Th_d_00048538-RA
uncharacterized family
31 glucosidase
KIAA1161-like
Paper 0.02
Th_d_00034779-RA hydrolase family 9 Paper 0.01
349
Table 4.2. Effect of diet on lytic polysaccharide monoxygenase (LPMO) gene expression in
foregut tissue of Thermobia domestica. Differentially expressed of LPMO genes in different
pair-wise treatment comparisons of foregut tissue of T. domestica fed on carboxymethyl
cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Up-regulated diet Padj value CMC vs Protein Coding sequence Th_d_00014400-RA CMC < 0.001 Th_d_00056727-RA CMC 0.03 Th_d_00064622-RA CMC 0.02 Th_d_00068335-RA CMC 0.02 Th_d_00109123-RA CMC 0.002 Th_d_00110473-RA CMC 0.04 Th_d_00120034-RA CMC 0.03 Paper vs Protein Coding sequence Th_d_00014400-RA Paper 0.005 Th_d_00023793-RA Paper < 0.001 Th_d_00032707-RA Paper 0.02 Th_d_00056072-RA Paper 0.01 Th_d_00056739-RA Paper 0.03 Th_d_00056740-RA Paper 0.003 Th_d_00058359-RA Paper 0.04 Th_d_00064622-RA Paper < 0.001 Th_d_00068335-RA Paper < 0.001 Th_d_00068347-RA Paper 0.03 Th_d_00071020-RA Paper 0.002 Th_d_00083583-RA Paper < 0.001 Th_d_00084210-RA Paper 0.005 Th_d_00092785-RA Paper 0.04 Th_d_00095724-RA Paper 0.03 Th_d_00108306-RA Paper 0.005 Th_d_00109123-RA Paper 0.01 Th_d_00110473-RA Paper 0.01 Th_d_00119312-RA Paper 0.02 Th_d_00120034-RA Paper 0.04 Th_d_00120998-RA Paper <0.001 Paper vs CMC Coding sequence Th_d_00007075-RA Paper 0.04
350
Table 4.2. Continued. Diets tested Up-regulated diet Padj value Th_d_00084210-RA Paper 0.04 Th_d_00120998-RA Paper 0.03 Switchgrass vs CMC Coding sequence Th_d_00014400-RA CMC < 0.001 Th_d_00064622-RA CMC 0.001 Th_d_00098297-RA CMC 0.04 Th_d_00104344-RA CMC 0.005 Th_d_00109123-RA CMC 0.003 Th_d_00110473-RA CMC 0.03 Th_d_00120034-RA CMC 0.03 Paper vs Switchgrass Coding sequence Th_d_00014400-RA Paper 0.04 Th_d_00037466-RA Paper <0.001 Th_d_00056739-RA Paper <0.001 Th_d_00056740-RA Paper 0.01 Th_d_00064622-RA Paper 0.002 Th_d_00071020-RA Paper <0.001 Th_d_00083583-RA Paper 0.04 Th_d_00092785-RA Paper 0.002 Th_d_00095665-RA Paper 0.003 Th_d_00095724-RA Paper 0.02 Th_d_00098297-RA Paper 0.03 Th_d_00108306-RA Paper <0.001 Th_d_00109123-RA Paper 0.004 Th_d_00110473-RA Paper 0.04 Th_d_00119312-RA Paper 0.03 Th_d_00120034-RA Paper 0.006 Th_d_00120998-RA Paper 0.01
351
Table 4.3. Effect of diet on plant cell wall degrading enzyme (PCWDE) gene expression in rest of the body sample of Thermobia domestica. Differentially expressed PCWDE genes in different pair-wise treatment comparisons of rest of the body sample of T. domestica fed on carboxymethyl cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Enzyme Up-regulated diet Padj value CMC vs Protein Coding sequence Th_d_00005705-RA hydrolase family 9
CMC 0.02
Th_d_00104189-RA hydrolase family 9
CMC 0.02
Paper vs Protein Coding sequence Th_d_00071154-RA hydrolase family 9
Paper < 0.001
Th_d_00029874-RA hydrolase family 9
Paper 0.003
Th_d_00041503-RA Endoglucanase
Paper 0.006
Th_d_00000348-RA Endoglucanase
Paper 0.002
Th_d_00018984-RA hydrolase family 9
Paper 0.04
Th_d_00045439-RA β-1,4-glucanase
Paper 0.008
Th_d_00031500-RA Endoglucanase
Paper 0.003
Th_d_00015659-RA hydrolase family 9
Paper 0.04
Th_d_00007226-RA β-1,4-endoglucanase 1
Paper 0.02
Th_d_00111221-RA hydrolase family 9
Paper 0.02
Th_d_00005705-RA hydrolase family 9
Paper < 0.001
Th_d_00104189-RA hydrolase family 9
Paper < 0.001
Th_d_00046715-RA hydrolase family 9
Paper < 0.001
Th_d_00028499-RA hydrolase family 9
Paper < 0.001
352
Table 4.3. Continued
Diets tested Enzyme Up-regulated diet Padj value Th_d_00034779-RA hydrolase family 9
Paper < 0.001
Switchgrass vs Protein
Coding sequence Th_d_00104189-RA hydrolase family 9
Switchgrass 0.02
Th_d_00035324-RA Endoglucanase
Switchgrass 0.001
Paper vs CMC Coding sequence Th_d_00035294-RA hydrolase family 9
Paper 0.04
Th_d_00071154-RA hydrolase family 9
Paper 0.002
Th_d_00029874-RA hydrolase family 9
Paper 0.01
Th_d_00018632-RA β-glucosidase
Paper 0.04
Th_d_00000353-RA hydrolase family 9
Paper < 0.001
Th_d_00107645-RA hydrolase family 9
Paper < 0.001
Th_d_00018984-RA hydrolase family 9
Paper 0.004
Th_d_00045439-RA β-1,4-glucanase
Paper < 0.001
Th_d_00101434-RA Mannanase
Paper 0.01
Th_d_00007226-RA β-1,4-endoglucanase 1
CMC 0.003
Th_d_00034779-RA hydrolase family 9
Paper 0.007
Switchgrass vs CMC
Coding sequence Th_d_00107645-RA hydrolase family 9
Switchgrass 0.02
353
Table 4.3. Continued.
Diets tested Enzyme Up-regulated diet Padj value Th_d_00035324-RA Endoglucanase
Switchgrass < 0.001
Paper vs Switchgrass
Coding sequence Th_d_00071154-RA hydrolase family 9
Paper < 0.001
Th_d_00029874-RA hydrolase family 9
Paper < 0.001
Th_d_00118343-RA hydrolase family 9
Paper 0.04
Th_d_00041503-RA Endoglucanase
Paper < 0.001
Th_d_00000348-RA Endoglucanase
Paper < 0.001
Th_d_00000353-RA hydrolase family 9
Paper < 0.001
Th_d_00000354-RA hydrolase family 9
Paper 0.04
Th_d_00018984-RA hydrolase family 9
Paper 0.01
Th_d_00007226-RA β-1,4-endoglucanase 1
Paper < 0.001
Th_d_00111221-RA hydrolase family 9
Paper 0.004
Th_d_00005705-RA hydrolase family 9
Paper 0.01
Th_d_00028499-RA hydrolase family 9
Paper < 0.001
Th_d_00038486-RA hydrolase family 9
Paper 0.002
Th_d_00034779-RA hydrolase family 9
Paper < 0.001
354
Table 4.4. Effect of diet on lytic polysaccharide monoxygenase (LPMO) gene expression in rest of the body sample of Thermobia domestica. Differentially expressed LPMO genes in different pair-wise treatment comparisons of rest of the body sample of T. domestica fed on carboxymethyl cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Up-regulated diet Padj value CMC vs Protein Coding sequence Th_d_00037467-RA CMC 0.03 Paper vs CMC Coding sequence Th_d_00056739-RA CMC < 0.001 Th_d_00068347-RA Paper 0.04 Th_d_00083583-RA CMC 0.04 Th_d_00120998-RA CMC 0.02 Paper vs switchgrass Coding sequence Th_d_00056739-RA Switchgrass < 0.001 Th_d_00056740-RA Paper 0.001 Th_d_00058638-RA Paper 0.02 Th_d_00068347-RA Paper 0.005 Th_d_00083583-RA Switchgrass 0.02 Th_d_00092785-RA Switchgrass 0.03 Th_d_00112968-RA Switchgrass 0.004 Th_d_00120998-RA Switchgrass 0.001
355
Table 4.5. Effect of diet on plant cell wall degrading enzyme (PCWDE) gene expression in foregut tissue of Ctenolepisma longicaudata. Differentially expressed PCWDE genes in different pair-wise treatment comparisons of foregut tissue of C. longicaudata fed on carboxymethyl cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Enzyme Up-regulated diet Padj value Paper vs Protein Coding sequence Lep_00006775-RA hydrolase family 9 Paper < 0.001 Lep_00022398-RA hydrolase family 9 Paper 0.02 Lep_00034744-RA hydrolase family 9 Paper 0.04 Lep_00036184-RA hydrolase family 9 Paper 0.002 Lep_00044891-RA hydrolase family 9 Paper 0.001 Lep_00051683-RA hydrolase family 9 Paper 0.005 Lep_00051684-RA hydrolase family 9 Paper 0.002 Lep_00052326-RA hydrolase family 9 Paper 0.003 Lep_00060202-RA hydrolase family 9 Paper 0.001 Lep_00071132-RA hydrolase family 9 Paper < 0.001 Lep_00071754-RA hydrolase family 9 Paper 0.005 Lep_00115213-RA hydrolase family 9 Paper 0.008 Lep_00135466-RA hydrolase family 9 Paper < 0.001 Switchgrass vs Protein
Coding sequence Lep_00006757-RA β-galactosidase-1 3 Switchgrass 0.04 Lep_00028614-RA β-glucuronidase Switchgrass 0.02 Lep_00055855-RA β-glucuronidase Switchgrass 0.001 Lep_00096399-RA hydrolase family 9 Protein 0.02 Paper vs CMC Coding sequence Lep_00006775-RA hydrolase family 9 Paper < 0.001 Lep_00012530-RA Mannanase CMC 0.04 Lep_00022398-RA hydrolase family 9 Paper 0.002
Lep_00034832-RA endo- β-1,4-glucanase
Paper 0.02
Lep_00036184-RA hydrolase family 9 Paper < 0.001 Lep_00044891-RA hydrolase family 9 Paper < 0.001 Lep_00060202-RA hydrolase family 9 Paper < 0.001 Lep_00071132-RA hydrolase family 9 Paper 0.001 Lep_00071461-RA hydrolase family 9 Paper < 0.001 Lep_00078550-RA hydrolase family 9 Paper < 0.001
356
Table 4.5. Continued.
Diets tested Enzyme Up-regulated diet Padj value
Lep_00104311-RA endo- β-1,4-glucanase
Paper 0.04
Lep_00115213-RA hydrolase family 9 Paper < 0.001 Lep_00135466-RA hydrolase family 9 Paper < 0.001 Switchgrass vs Paper Coding sequence
Lep_00029521-RA endo- β-1,4-glucanase
Paper 0.005
Lep_00036184-RA hydrolase family 9 Paper 0.005
Lep_00039163-RA β-1,3-glucan-binding -like
Paper < 0.001
Lep_00071461-RA hydrolase family 9 Paper < 0.001 Lep_00078550-RA hydrolase family 9 Paper < 0.001 Lep_00135466-RA hydrolase family 9 paper < 0.001
357
Table 4.6. Effect of diet on lytic polysaccharide monoxygenase (LPMO) gene expression in foregut tissue of Ctenolepisma longicaudata. Differentially expressed lytic polysaccharide monoxygenases (LPMOs) genes in different pair-wise treatment comparisons of foregut tissue of C. longicaudata fed on carboxymethyl cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Up-regulated diet Padj value Paper vs Protein Coding sequence Lep_00018140-RA Paper 0.04 Lep_00029394-RA Paper 0.03 Lep_00037556-RA Paper < 0.001 Lep_00039537-RA Paper 0.006 Lep_00083016-RA Paper 0.02 Lep_00084324-RA Paper 0.02 Lep_00097915-RA Paper 0.03 Lep_00103234-RA Paper 0.02 Lep_00106678-RA Paper < 0.001 Lep_00118447-RA Paper 0.005 Lep_00136402-RA Paper 0.04 Switchgrass vs Protein Coding sequence Lep_00083016-RA Switchgrass 0.005 Lep_00097788-RA Switchgrass 0.04 Lep_00119656-RA Switchgrass 0.04 Paper vs CMC Coding sequence Lep_00110038-RA CMC 0.04 Switchgrass vs CMC Coding sequence Lep_00121885-RA Switchgrass 0.02
358
Table 4.7. Effect of diet on plant cell wall degrading enzyme (PCWDE) gene expression in rest of the body sample of Ctenolepisma longicaudata. Differentially expressed PCWDE genes in different pair-wise treatment comparisons of rest of the body sample of C. longicaudata fed on carboxymethyl cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Enzyme Up-regulated diet Padj value CMC vs Protein Coding sequence Lep_00004873-RA Glucosidase CMC 0.04 Lep_00011407-RA Glucosidase Protein 0.04 Lep_00015101-RA Glucosidase CMC 0.02 Lep_00020108-RA Glucosidase CMC 0.006 Lep_00026156-RA hydrolase family 9 CMC 0.03 Lep_00036877-RA β-galactosidase-1 2 CMC 0.03 Lep_00038648-RA hydrolase family 9 CMC 0.04 Lep_00052604-RA Glucosidase CMC 0.002 Lep_00059101-RA β-galactosidase-1 2 CMC 0.006
Lep_00079073-RA
uncharacterized family 31 glucosidase KIAA1161-like
CMC 0.001
Lep_00094746-RA
uncharacterized family 31 glucosidase KIAA1161-like
uncharacterized family 31 glucosidase KIAA1161-like
CMC < 0.001
Paper vs Protein Coding sequence Lep_00004872-RA Glucosidase Protein 0.002 Lep_00006775-RA hydrolase family 9 Paper < 0.001 Lep_00026154-RA Endoglucanase Protein 0.04 Lep_00026156-RA hydrolase family 9 Protein < 0.001 Lep_00036184-RA hydrolase family 9 Paper < 0.001 Lep_00042852-RA hydrolase family 9 Paper < 0.001 Lep_00059101-RA β-galactosidase-1 2 Protein 0.04 Lep_00060202-RA hydrolase family 9 Paper 0.005 Lep_00071461-RA hydrolase family 9 Paper < 0.001 Lep_00078550-RA hydrolase family 9 Paper < 0.001
359
Table 4.7. Continued.
Diets tested Enzyme Up-regulated diet Padj value
Lep_00102111-RA
uncharacterized family 31 glucosidase KIAA1161-like
Protein 0.04
Lep_00113088-RA Glucosidase Paper 0.008 Lep_00135466-RA hydrolase family 9 Paper < 0.001 Switchgrass vs Protein
Coding sequence Lep_00004872-RA Glucosidase Protein 0.04 Lep_00014981-RA hydrolase family 9 Protein 0.004 Lep_00014982-RA β-1,4-glucanase 5 Protein 0.003 Lep_00014983-RA hydrolase family 9 Protein 0.03 Lep_00021305-RA Glucosidase Switchgrass 0.04
Lep_00034316-RA β-1,3-glucan-binding -like
Switchgrass 0.04
Lep_00036877-RA β-galactosidase-1 2 Protein 0.03 Lep_00042852-RA hydrolase family 9 Switchgrass < 0.001 Lep_00050000-RA hydrolase family 65 Switchgrass 0.003 Lep_00065284-RA Glucosidase Switchgrass 0.003
Lep_00077538-RA
uncharacterized family 31 glucosidase KIAA1161-like
Protein 0.04
Lep_00079073-RA
uncharacterized family 31 glucosidase KIAA1161-like
Protein 0.03
Lep_00095117-RA endo- β-1,4-glucanase Switchgrass 0.005 Lep_00096399-RA hydrolase family 9 Protein <0.001
Lep_00102111-RA
uncharacterized family 31 glucosidase KIAA1161-like
Protein < 0.001
Lep_00113088-RA Glucosidase Protein < 0.001 Paper vs CMC Coding sequence Lep_00006775-RA hydrolase family 9 Paper < 0.001 Lep_00015101-RA Glucosidase Paper < 0.001 Lep_00022398-RA hydrolase family 9 Paper 0.001 Lep_00024218-RA β-1,6-glucanase Paper 0.04 Lep_00036184-RA hydrolase family 9 Paper < 0.001
360
Table 4.7. Continued.
Diets tested Enzyme Up-regulated diet Padj value Lep_00038648-RA hydrolase family 9 Paper < 0.001 Lep_00042851-RA hydrolase family 9 Paper 0.04 Lep_00044891-RA hydrolase family 9 Paper < 0.001 Lep_00051683-RA hydrolase family 9 Paper 0.004 Lep_00051684-RA hydrolase family 9 Paper < 0.001 Lep_00052326-RA hydrolase family 9 Paper < 0.001 Lep_00060202-RA hydrolase family 9 Paper < 0.001 Lep_00071132-RA hydrolase family 9 Paper < 0.001 Lep_00071461-RA hydrolase family 9 Paper < 0.001 Lep_00071754-RA hydrolase family 9 Paper < 0.001 Lep_00078550-RA hydrolase family 9 Paper < 0.001 Lep_00082758-RA Glucosidase Paper 0.004 Lep_00115213-RA hydrolase family 9 Paper < 0.001 Lep_00135466-RA hydrolase family 9 Paper < 0.001 Switchgrass vs CMC Coding sequence Lep_00004873-RA Glucosidase Switchgrass 0.04 Lep_00015101-RA Glucosidase Switchgrass < 0.001 Lep_00016310-RA hydrolase family 9 CMC < 0.001 Lep_00016311-RA endo- β-1,4-glucanase CMC < 0.001 Lep_00016312-RA hydrolase family 9 CMC < 0.001 Lep_00019550-RA Glucosidase Switchgrass 0.03 Lep_00020108-RA Glucosidase Switchgrass 0.04 Lep_00021305-RA Glucosidase Switchgrass 0.04 Lep_00022398-RA hydrolase family 9 Switchgrass 0.002 Lep_00024904-RA Glucosidase Switchgrass 0.001 Lep_00026029-RA β-galactosidase Switchgrass 0.03 Lep_00028613-RA β-glucuronidase-like Switchgrass 0.004 Lep_00028614-RA β-glucuronidase Switchgrass < 0.001
Lep_00034316-RA β-1,3-glucan-binding -like
Switchgrass 0.04
Lep_00036380-RA Glucosidase Switchgrass 0.03 Lep_00038648-RA hydrolase family 9 Switchgrass < 0.001 Lep_00042851-RA hydrolase family 9 Switchgrass 0.03 Lep_00042852-RA hydrolase family 9 Switchgrass 0.002 Lep_00046431-RA β-glucuronidase Switchgrass 0.04 Lep_00048639-RA Glucosidase Switchgrass 0.03 Lep_00050000-RA hydrolase family 65 Switchgrass 0.004
uncharacterized family 31 glucosidase KIAA1161-like
Switchgrass 0.03
Lep_00095117-RA endo- β-1,4-glucanase Switchgrass 0.007 Lep_00097528-RA Glucosidase 0.04 Paper vs Switchgrass Coding sequence Lep_00006775-RA hydrolase family 9 Paper < 0.001 Lep_00008899-RA β-galactosidase-1 3 Switchgrass 0.03 Lep_00014981-RA hydrolase family 9 Paper 0.007 Lep_00014982-RA β-1,4-glucanase 5 Paper 0.002 Lep_00014983-RA hydrolase family 9 Paper 0.03 Lep_00015051-RA Mannanase Switchgrass 0.007 Lep_00016310-RA hydrolase family 9 Paper 0.003 Lep_00016311-RA endo- β-1,4-glucanase Paper 0.001 Lep_00016312-RA hydrolase family 9 Paper < 0.001 Lep_00036184-RA hydrolase family 9 Paper < 0.001 Lep_00044891-RA hydrolase family 9 Paper 0.003 Lep_00060202-RA hydrolase family 9 Paper < 0.001 Lep_00071132-RA hydrolase family 9 Paper 0.01 Lep_00071461-RA hydrolase family 9 Paper < 0.001
Lep_00074516-RA
uncharacterized family 31 glucosidase KIAA1161-like
Switchgrass 0.04
362
Table 4.7. Continued.
Diets tested Enzyme Up-regulated diet Padj value Lep_00078550-RA hydrolase family 9 Paper < 0.001 Lep_00096399-RA hydrolase family 9 Paper < 0.001 Lep_00115213-RA hydrolase family 9 Paper 0.002 Lep_00135466-RA hydrolase family 9 Paper 0.008
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Table 4.8. Effect of diet on lytic polysaccharide monoxygenase (LPMO) gene expression in rest of the body sample of Ctenolepisma longicaudata. Differentially expressed LPMO genes in different pair-wise treatment comparisons of rest of the body sample of C. longicaudata fed on carboxymethyl cellulose (CMC), paper, protein and switchgrass diets (Padj < 0.05).
Diets tested Up-regulated diet Padj value Switchgrass vs Protein Coding sequence Lep_00006589-RA Switchgrass 0.004 Lep_00037556-RA Switchgrass < 0.001 Lep_00071838-RA Switchgrass < 0.001 Lep_00078707-RA Switchgrass 0.01 Lep_00099093-RA Switchgrass 0.006 Lep_00127363-RA Switchgrass 0.02 Paper vs CMC Coding sequence Lep_00018140-RA Paper < 0.001 Lep_00030922-RA Paper < 0.001 Lep_00030924-RA Paper < 0.001 Lep_00037556-RA Paper 0.04 Lep_00072794-RA Paper 0.02 Lep_00083283-RA Paper 0.02 Switchgrass vs CMC Coding sequence Lep_00006587-RA Switchgrass 0.04 Lep_00006588-RA Switchgrass 0.04 Lep_00006589-RA Switchgrass 0.02 Lep_00006590-RA Switchgrass 0.03 Lep_00018140-RA Switchgrass 0.005 Lep_00029394-RA Switchgrass 0.04 Lep_00037556-RA Switchgrass 0.01 Lep_00039537-RA Switchgrass < 0.001 Lep_00043371-RA Switchgrass 0.03 Lep_00060573-RA Switchgrass 0.03 Lep_00072794-RA Switchgrass < 0.001 Lep_00083283-RA Switchgrass < 0.001 Lep_00093845-RA Switchgrass 0.04 Lep_00099441-RA Switchgrass 0.03 Lep_00103234-RA Switchgrass 0.001 Lep_00109934-RA Switchgrass 0.002 Lep_00119656-RA Switchgrass 0.01
364
Table 4.8. Continued.
Diets tested Up-regulated diet Padj value Lep_00127363-RA Switchgrass 0.02 Paper vs Switchgrass Coding sequence Lep_00006587-RA Switchgrass 0.001 Lep_00006588-RA Switchgrass 0.03 Lep_00006589-RA Switchgrass 0.02 Lep_00039538-RA Switchgrass 0.02 Lep_00127363-RA Switchgrass 0.04
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Table 4.9. Differentially expressed plant cell wall degrading enzyme (PCWDE) gene in Thermobia domestica and their top-blast hit. Significantly differentially expressed PCWDE genes (Padj < 0.05) were blasted against the NCBInr database, and the matching protein and the tissue in T. domestica are listed.
Table 4.10. Differentially expressed plant cell wall degrading enzyme (PCWDE) genes in Ctenolepisma longicaudata and their top-blast hit. Significantly differentially expressed PCWDEs (Padj < 0.05) were blasted against NCBInr database, and the matching protein and tissue in C. longicaudata are listed.
Sequence_Id
Identified protein
Organism Query cover
E value
% identity
Accession Sample
Lep_00044891-RA
Uncharacterized protein LOC110840536 (endo-β-1,4-glucanase)
Zootermopsis nevadensis
94 0.0 66 XP_021941324.1
Both
Lep_00098705-RA
β-glucosidase
Acanthaster planci
25 5e-07
55 XP_022090546.1
Rest of the body
Lep_00077538-RA
α-glucosidase family 31
Periplaneta americana
89 0.0 53 AIA09350.1 Rest of the body
Lep_00087818-RA
Hypothetical protein LOTGIDRAFT 101222 (endo-β-1,6-glucanase)
Lottia gigantea
70 3e-122
49 XP_009054280.1
Rest of the body
Lep_00036380-RA
Myrosinase 1-like (β-glucosidase)
Cryptotermes secundus
88 2e-104
50 XP_023721112.1
Rest of the body
Lep_00115213-RA
Endoglucanase 7-like
Zootermopsis nevadensis
84 1e-80
72 XP_021941322.1
Both
Lep_00004872-RA
β-glucosidase
Coptotermes formosanus
76 2e-145
56 AOY34571.1 Rest of the body
370
Table 4.10. Continued.
Sequence_Id
Identified protein
Organism Query cover
E value
% identity
Accession Sample
Lep_00004873-RA
Myrosinase 1-like (β-glucosidase)
Cryptotermes secundus
94 8e-50 68 XP_023723774.1
Rest of the body
Lep_00065345-RA
β-glucuronidase-like
Centruroides sculpturatus
49 2e-11 51 XP_023221887.1
Rest of the body
Lep_00071461-RA
Uncharacterized protein LOC110840536 (endo-β-1,4-glucanase)
Zootermopsis nevadensis
94 1e-105
72 XP_021941324.1
Both
Lep_00019550-RA
Hypothetical protein B5V51_11090 (β-glucosidase)
Heliothis virescens
74 8e-50 34 PCG75727.1 Rest of the body
Lep_00021305-RA
Chain A, Crystal Structure of β-Glucosidase From Termite Neotermes Koshunensis in complex with Tris
Neotermes koshunensis
83 3e-92 59 3AHZ_A Rest of the body
Lep_00048639-RA
β-glucosidase Salganea esakii
59 7e-24 55 BAO85048.1 Rest of the body
371
Table 4.10. Continued.
Sequence_Id
Identified protein
Organism Query cover
E value
% identity
Accession
Sample
Lep_00053738-RA
Hypothetical protein B7P43_G09739 (β-glucuronidase)
Cryptotermes secundus
88 1e-67 62 PNF22051.1
Rest of the body
Lep_00059101-RA
β -galactosidase-1-like protein 2
Cephus cinctus
74 9e-65 51 XP_015598574.1
Rest of the body
Lep_00071754-RA
Endoglucanase E-4
Blattella germanica
77 6e-79 60 PSN33998.1
Both
Lep_00055855-RA
Hypothetical protein B7P43_G09739 (β-glucuronidase)
Cryptotermes secundus
96 9e-68 62 PNF22051.1
Foregut
Lep_00016310-RA
Endoglucanase 7-like
Zootermopsis nevadensis
84 8e-75 71 XP_021941322.1
Rest of the body
Lep_00016311-RA
Cellulase Coptotermes acinaciformis
71 3e-55 58 AAK12339.1
Rest of the body
Lep_00016312-RA
Endoglucanase E-4
Blattella germanica
38 8e-44 65 PSN33998.1
Rest of the body
Lep_00074516-RA
Hypothetical protein B7P43_G04891 (Uncharacterized family 31 glucosidase)
Cryptotermes secundus
89 1e-147
47 PNF32421.1
Rest of the body
Lep_00065284-RA
β-glucosidase Coptotermes formosanus
83 1e-60 50 AGM32287.1
Rest of the body
372
Table 4.10. Continued.
Sequence_Id
Identified protein
Organism Query cover
E value
% identity
Accession
Sample
Lep_00052326-RA
Uncharacterized protein LOC110840536 (endo-β-1,4-glucanase)
Zootermopsis nevadensis
83 1e-98 50 XP_021941324.1
Both
Lep_00006757-RA
β -galactosidase-1-like protein 2
Cephus cinctus
32 4e-62 52 XP_015598574.1
Foregut
Lep_00034744-RA
Glycoside hydrolase family 9
Peruphasma schultei
86 1e-147
50 AMH40374.1
Foregut
Lep_00015101-RA
Myrosinase 1-like (β-glucosidase)
Cryptotermes secundus
96 4e-147
50 XP_023721112.1
Rest of the body
Lep_00014981-RA
Cellulase Antipaluria urichi
31 4e-58 57 AOV94250.1
Rest of the body
Lep_00014982-RA
Putative endo-β-1,4-glucanase of EG1
Odontotermes formosanus
82 5e-77 56 BAD12008.1
Rest of the body
Lep_00014983-RA
Predicted protein (endo-β-1,4-glucanase)
Nematostella vectensis
31 7e-23 78 XP_001640311.1
Rest of the body
Lep_00071132-RA
Uncharacterized protein LOC110840536 (endo-β-1,4-glucanase)
Zootermopsis nevadensis
95 3e-104
72 XP_021941324.1
Both
Lep_00051683-RA
Glycoside hydrolase family 9
Timema cristinae
90 1e-23 64 AMH40395.1
Both
373
Table 4.10. Continued.
Sequence_Id
Identified protein
Organism Query cover
E value
% identity
Accession
Sample
Lep_00051684-RA
β-1,4-endoglucanase 1
Panesthia cribrate
94 8e-36 63 AAF80584.1
Both
Lep_00079073-RA
Hypothetical protein C0J52_14633 (Uncharacterized family 31 glucosidase)
Blatella germanica
60 2e-20 65 PSN31308.1
Rest of the body
Lep_00104311-RA
Hypothetical protein C0J52_21511 (endo-β-1,4-glucanase
Blatella germanica
99 2e-55 57 PSN31180.1
Foregut
Lep_00046431-RA
β-glucuronidase-like isoform X3
Cryptotermes secundus
86 3e-123
57 XP_023718877.1
Rest of the body
Lep_00028614-RA
β-glucuronidase-like isoform X3
Cryptotermes secundus
91 1e-69 52 XP_023718877.1
Both
Lep_00028613-RA
β-glucuronidase-like
Halyomorpha halys
42 6e-46 72 XP_024217164.1
Rest of the body
Lep_00095117-RA
Putative endo- β-1,4-glucanase SmEG1
Sinocapritermes mushae
99 1e-47 53 BAD12012.1
Rest of the body
Lep_00060393-RA
β-glucosidase Coptotermes formosanus
81 5e-55 70 AGM32308.1
Rest of the body
Lep_00039163-RA
Hypothetical protein D910_11210 (β-1,3-glucanase)
Dendroctonus ponderosae
68 1e-09 44 ERL93924.1
Foregut
374
Table 4.10. Continued.
Sequence_Id
Identified protein
Organism Query cover
E value
% identity
Accession
Sample
Lep_00082758-RA
Lactase-phlorizin hydrolase-like (β-glucosidase)
Acanthochromis polyacanthus
90 6e-09 30 XP_022078461.1
Rest of the body
Lep_00038648-RA
Glycoside hydrolase family 9
Ramulus artemis
35 5e-22 65 AMH40383.1
Rest of the body
Lep_00034316-RA
Hypothetical protein DAPPUDRAFT_203138 (β-1,3-glucanase)
Daphnia pulex
49 3e-36 42 EFX69036.1
Rest of the body
Lep_00060202-RA
Endoglucanase E-4
Blattella germanica
73 2e-91 62 PSN33998.1
Both
Lep_00022398-RA
Glycoside hydrolase family 9
Timema cristinae
88 5e-176
61 AMH40392.1
Both
Lep_00026029-RA
Hypothetical protein B7P43_G16708 (β-galactosidase)
Cryptotermes secundus
66 7e-65 58 PNF39271.1
Rest of the body
Lep_00036184-RA
Uncharacterized protein LOC110840536 (endo- β-1,4-glucanase)
Figure 4.1. Heatmap of expression of of all differentially expressed PCWDE genes in Thermobia domestica: heatmap showing the significantly differentially expressed PCWDE genes in T. domestica foregut (FGUT) and rest of the body samples (REST) fed on carboxymethyl cellulose (CMC), paper (PAP), protein (PRO) and switchgrass (SG) diets (Padj < 0.05).
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Figure 4.2. Heatmap of expression of all differentially expressed PCWDE genes in Ctenolepisma longicaudata: heatmap showing the significantly differentially expressed PCWDEs in C. longicaudata foregut (FGUT) and rest of the body samples (REST) fed on carboxymethyl cellulose (CMC), paper (PAP), protein (PRO) and switchgrass (SG) diets (Padj < 0.05).
380
Figure 4.3. Overall effect of tissue (PC1) and condition (diet, PC2) on gene expression of lytic polysaccharide monoxygenases (LPMOs) in Thermobia domestica: PCA plot showing the strong effect of tissue compared to diet on the gene expression of significantly differentially expressed LPMOs in foregut (FGUT) and rest of the body (REST) tissues of T. domestica fed on carboxymethyl cellulose (CMC), paper (PAP), protein (PRO) and switchgrass (SG) diets (Padj < 0.05).
381
Figure 4.4. Differential expression of all lytic polysaccharide momoxygenases (LPMOs) in Thermobia domestica: heatmap showing the significantly differentially expressed LPMOs in T. domestica foregut (FGUT) and rest of the body samples (REST) fed on carboxymethyl cellulose (CMC), paper (PAP), protein (PRO) and switchgrass (SG) diets (Padj < 0.05).
382
Figure 4.5. Overall effect of tissue (PC1) and condition (diet, PC2) on gene expression of lytic polysaccharide monoxygenases (LPMOs) in Ctenolepisma longicaudata: PCA plot showing the strong effect of tissue compared to diet on the gene expression of significantly differentially expressed LPMOs in foregut (FGUT) and rest of the body (REST) tissues of C. longicaudata fed on carboxymethyl cellulose (CMC), paper (PAP), protein (PRO) and switchgrass (SG) diets (Padj < 0.05).
383
Figure 4.6. Differential expression of all lytic polysaccharide momoxygenases (LPMOs) in Ctenolepisma longicaudata: heatmap showing the significantly differentially expressed LPMOs in C. longicaudata foregut (FGUT) and rest of the body samples (REST) fed on carboxymethyl cellulose (CMC), paper (PAP), protein (PRO) and switchgrass (SG) diets (Padj < 0.05).
384
Chapter 5
General conclusions
385
Conclusions
Our research focused on Thermobia domestica and Ctenolepisma longicaudata and
unraveled many interesting observations about these two species. Initial
morphohistological characterization supported no relevant morphological and histological
adaptations to house symbionts in the digestive system of firebrat (T. domestica) and the
gray silverfish (C. longicaudata), which may suggest the endogenous production of
cellulases in these insects. Previous studies supported the endogenous digestion of
cellulose in the firebrat (Treves and Martin, 1994; Zinkler and Götze, 1987). Additionally,
no morphohistological differences were found in the digestive tube of both the tested
species.
Significant differences were observed in cellulase activities between species.
Quantitative and qualitative cellulase assays identified the foregut as the region with the
highest cellulolytic activity compared to other digestive regions in both the species. This
observation is also supported by previous reports documenting higher endoglucanase and
β-glucosidase activities in the foregut compared to other gut tissues in T. domestica
(Zinkler and Gotze, 1987). Additionally, T. domestica was found displaying higher
endoglucanase, xylanase activities compared to C. longicaudata and pectinase activity was
only observed in T. domestica. However, pectinase genes were not detected in the
corresponding T. domestica genome. A possible explanation for this discrepancy could be
that pectinase activity in T. domestica may be provided by microorganisms living in its
digestive system, which were not included in the genome sequencing. Metatranscriptomics
386
on the microbiome of T. domestica will help in determing the contribution of microbial
enzymes to pectinase digestion in T. domestica. Alternatively, it is possible that pectinase
genes may be included among the sequences not returing relevant BLAST matches in our
Blast2Go analysis. Searches using conserved pectinase catalytic domains may allow
identification of pectinase-like sequences in Zygentoma genomes. On the other hand, the
lack of pectinase activity in C. longicauadata may suggest that this polysaccharide is not
relevant to its nutrition.
T. domestica also displayed significantly higher xylanase activity than C.
longicaudata. However, genes encoding for xylanases were not detected in T. domestica
genome and only three xylanase encoding genes were found in the genome of C.
longicauadata. Many insects including T. domestica were previously found to display
xylanase activity (Sabbadin et al., 2018; Shi et al., 2011; Terra and Ferreira, 1994), yet
xylanases are rarely described as endogenously produced in insects (Calderón-Cortés et al.,
2012) and in most instances expected to come from symbiotic microbiota (Ali et al., 2017;
Brennan et al., 2004) or through horizontal gene transfer from symbionts (Pauchet and
Heckel, 2013). Sequencing the metatranscriptome of T. domestica and C. longicaudata gut
microbiota would help in understanding the source of xylanase activity in these insects. It
is also possible that hemicellulose could be digested in insects by other enzymes, such as
mannanases, α-glucuronidases, endoglucanases and β-1,3-glucanases(Calderón-Cortés et
al., 2012), which were present in the genomes of both species.
387
Zygentoma displayed relatively high cellulolytic activity compared to other insects
(Pothula et al, submitted), which may be explained by the detected genes encoding for
diverse glycosyl hydrolases in their genomes. Consequently, annotation of coding
sequences from the genomes of T. domestica and C. longicaudata reported numerous genes
encoding for endoglucanases, glucosidases, β-1,3-glucanases, maltases, amylases,
mannosidases and glucuronidases. Compared to C. longicaudata, T. domestica had more
sequences encoding for endoglucanases, which may explain the higher endoglucanase
activity reported in T. domestica than C. longicaudata. Additionally, both species yielded
nearly an equal number of β-glucosidase genes, which was reflected in similar enzyme
activity levels. Apart from glycosyl hydrolases, lytic polysaccharide monoxygenases
(LPMOs), which were shown to enhance the activity of glycoside hydrolases synergistically
(Sabbadin et al., 2018) were abundantly reported in the genomes of both species. The
presence of high number of genes encoding LPMOs may also be responsible for higher
enzyme activities in Zygentoma compaed to other tested insects.
Differential gene expression analysis was conducted to see the influence of diet on
the gene expression of glycoside hydrolases and LPMOs in both foregut and rest of the body
samples of both T. domestica and C. longicaudata. PCWDE gene expression was primarily
driven by type of tissue rather than diet, yet within each tissue higher number of PCWDEs
were significantly up-regulated in paper-fed insects, which is more cellulosic compared to
all other tested diets. In addition, more LPMOs were up-regulated in the foregut tissue of
paper-fed T. domestica than other diets, yet LPMO up-regulation was not as prominent in C.
388
longicaudata. The paper diet used majorly consists of recalcitrant cellulose and traces of
hemicellulose and lignin, while switchgrass diet was composed of a variety of components
such as recalcitrant cellulose, hemicellulose, lignin along with easily digestible starch,
vitamins and minerals (Ververis et al., 2004). The availability of only recalcitrant cellulose
in paper may be responsible for up-regulation of majority of PCWDEs to digest more
cellulose in meeting energy requirements by insects.
The annotation of differentially expressed PCWDE and LPMO encoding genes
revealed highest identity to insect homologs, which suggests the potential conservation of
PCWDEs through evolution.
Overall, our work reports that members of Zygentoma display cellulase, xylanase
and pectinase activities. Digestive fluids of T. domestica appeared significantly more active
than in C. longicaudata, although in both insects the highest levels of digestion were
detected in the foregut. Additionally, both species were found as containing repertoires of
numerous and diverse PCWDE and LPMO genes. However, cellulase gene expression and
LPMOs was strongly driven by tissue in T. domestica and C. longicaudata. We contribute to
increasing the amount of information available on functional PCWDE genes and LPMOs
from a primitive hexapod group, which will help in characterizing more efficient cellulases.
In contrast to existing commercial cellulases, insect cellulases were reported to retain their
highest activity at alkaline pH (Willis et al., 2011). This unique trait makes it possible to
combine these enzymes with ionic liquids used for lignin digestion in biorefineries (Zhao et
al., 2009, 2008). In the future, cloning and expression of these PCWDE and LPMO genes in
389
heterologous systems such as yeast and testing their activity under different temperature
and pH regimes may help in identifying efficient cellulases with potential for industrial
biofuel applications.
390
Vita
Ratnasri Mallipeddi is originally from India and graduated with a B.Sc. degree in
Agricultural sciences form the Acharya N. G. Ranga Agricultural University, Hyderabad,
India. She later obtained her M.Sc. degree in Entomology from the University of Agricultural
Sciences, Dharwad, India. Upon graduation, she worked as a Research Associate at the
Maharastra Hybrid Coorpation (MAHYCO) in India. Later, she was accepted into the
Entomology, Plant Pathology and Nematology PhD program at the University of Tennessee
at Knoxville under the guidance of Dr. Juan Luis Juarat-Fuentes.